DIGITAL.CSIChttps://digital.csic.esThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Mon, 17 Jun 2019 11:39:55 GMT2019-06-17T11:39:55Z501261- Nonadiabatic state-to-state reactive collisions among open shell reactants with conical intersections: the OH(2Π) + F(2P) example†http://hdl.handle.net/10261/28219Title: Nonadiabatic state-to-state reactive collisions among open shell reactants with conical intersections: the OH(2Π) + F(2P) example†
Authors: Zanchet, Alexandre; González-Lezana, Tomás; Aguado, Alfredo; Gómez Carrasco, Susana; Roncero, Octavio
Abstract: Accurate wave packet calculations on the OH(2Π) + F(2P) → O(3P) + HF(1Σ+) reactive collisions are performed using a recently proposed coupled diabatic states. Adiabatic and nonadiabatic dynamics are compared in detail, analyzing the final state distribution of products. It is found that with the new surfaces a significant increase of the rate constant is obtained, with noticeable nonadiabatic effects. The inclusion of the spin−orbit splittings for the calculation of the electronic partition function produces an important increase of the reaction rate constants, yielding a rather good agreement with the experimental results. It is also concluded that spin−orbit couplings are also necessary in the entrance channel to describe this reaction.
Description: 10 pags. ; 10 figs. This article is part of the A: Reinhard Schinke Festschrift special issue.
Wed, 06 Oct 2010 08:14:41 GMThttp://hdl.handle.net/10261/282192010-10-06T08:14:41Z
- On the dynamics of the H(+) + D2(v=0, j=0) --> HD + D(+) reaction: A comparison between theory and experimenthttp://hdl.handle.net/10261/14391Title: On the dynamics of the H(+) + D2(v=0, j=0) --> HD + D(+) reaction: A comparison between theory and experiment
Authors: Carmona-Novillo, Estela; González-Lezana, Tomás; Roncero, Octavio; Honvault, Pascal; Launay, Jean-Michel; Bulut, Niyazi; Aoiz, F. Javier; Bañares, Luis; Trottier, Alexandre; Wrede, Eckart
Abstract: The H(+) + D2(v=0,j=0) --> HD + D(+) reaction has been theoretically investigated by means of a time independent exact quantum mechanical approach, a quantum wave packet calculation within an adiabatic centrifugal sudden approximation, a statistical quantum model, and a quasiclassical trajectory calculation. Besides reaction probabilities as a function of collision energy at different values of the total angular momentum, J, special emphasis has been made at two specific collision energies, 0.1 and 0.524 eV. The occurrence of distinctive dynamical behavior at these two energies is analyzed in some detail. An extensive comparison with previous experimental measurements on the Rydberg H atom with D2 molecules has been carried out at the higher collision energy. In particular, the present theoretical results have been employed to perform simulations of the experimental kinetic energy spectra.
Description: 15 pages, 12 figures, 2 tables.-- PACS nr.: 82.30.Fi.
Mon, 06 Jul 2009 10:24:52 GMThttp://hdl.handle.net/10261/143912009-07-06T10:24:52Z
- Quantum approaches for the insertion dynamics of the H(+) + D2 and D(+) + H2 reactive collisionshttp://hdl.handle.net/10261/14385Title: Quantum approaches for the insertion dynamics of the H(+) + D2 and D(+) + H2 reactive collisions
Authors: González-Lezana, Tomás; Aguado, Alfredo; Paniagua, Miguel; Roncero, Octavio
Abstract: The H(+) + D2 and D(+) + H2 reactive collisions are studied using a recently proposed adiabatic potential energy surface of spectroscopic accuracy. The dynamics is studied using an exact wave packet method on the adiabatic surface at energies below the curve crossing occurring at ≈ 1.5 eV above the threshold. It is found that the reaction is very well described by a statistical quantum method for a zero total angular momentum (J) as compared with the exact ones, while for higher J some discrepancies are found. For J>0 different centrifugal sudden approximations are proposed and compared with the exact and statistical quantum treatments. The usual centrifugal sudden approach fails by considering too high reaction barriers and too low reaction probabilities. A new statistically modified centrifugal sudden approach is considered which corrects these two failures to a rather good extent. It is also found that an adiabatic approximation for the helicities provides results in very good agreement with the statistical method, placing the reaction barrier properly. However, both statistical and adiabatic centrifugal treatments overestimate the reaction probabilities. The reaction cross sections thus obtained with the new approaches are in rather good agreement with the exact results. In spite of these deficiencies, the quantum statistical method is well adapted for describing the insertion dynamics, and it is then used to evaluate the differential cross sections.
Description: 13 pages, 10 figures.-- PACS nrs.: 82.30.Fi; 82.30.Nr; 82.20.Pm; 82.20.Kh.
Mon, 06 Jul 2009 09:59:14 GMThttp://hdl.handle.net/10261/143852009-07-06T09:59:14Z
- A detailed quantum mechanical and quasiclassical trajectory study on the dynamics of the H(+) + H2 --> H2 + H(+) exchange reactionhttp://hdl.handle.net/10261/14378Title: A detailed quantum mechanical and quasiclassical trajectory study on the dynamics of the H(+) + H2 --> H2 + H(+) exchange reaction
Authors: González-Lezana, Tomás; Roncero, Octavio; Honvault, Pascal; Launay, Jean-Michel; Bulut, Niyazi; Aoiz, F. Javier; Bañares, Luis
Abstract: The H(+) + H2 exchange reaction has been studied theoretically by means of a different variety of methods as an exact time independent quantum mechanical, approximate quantum wave packet, statistical quantum, and quasiclassical trajectory approaches. Total and state-to-state reaction probabilities in terms of the collision energy for different values of the total angular momentum obtained with these methods are compared. The dynamics of the reaction is extensively studied at the collision energy of E(coll) = 0.44 eV. Integral and differential cross sections and opacity functions at this collision energy have been calculated. In particular, the fairly good description of the exact quantum results provided by the statistical quantum method suggests that the dynamics of the process is governed by an insertion mechanism with the formation of a long-lived collision complex.
Description: 13 pages, 11 figures.-- PACS nrs.: 82.30.Hk; 82.30.Nr.
Mon, 06 Jul 2009 09:12:18 GMThttp://hdl.handle.net/10261/143782009-07-06T09:12:18Z
- Energy dependent dynamics of the O(1D) + HCl reaction: A quantum, quasiclassical and statistical studyhttp://hdl.handle.net/10261/58221Title: Energy dependent dynamics of the O(1D) + HCl reaction: A quantum, quasiclassical and statistical study
Authors: Bargueño, Pedro; Jambrina, P. G.; Alvariño, José M.; Menéndez, M.; Verdasco, E.; Hankele, M.; Smith, S.C..; Aoiz, F. Javier; González-Lezana, Tomás
Abstract: The dynamics of the reaction O(1D) + HCl → ClO + H, OH + Cl has been investigated in detail by means of a time-dependent wave packet (TDWP) method in comparison with quasiclassical trajectory (QCT) and statistical approaches on the ground potential energy surface by Martínez et al. [Phys. Chem. Chem. Phys., 2000, 2, 589]. Fully coupled quantum mechanical (QM) reaction probabilities for high values of the total angular momentum (J ≤ 50) are reported for the first time. At the low collision energy regime (E c ≤ 0.4 eV) the TDWP probabilities are well reproduced by the QCT and statistical results for the ClO forming product channel, but for the OH + Cl arrangement, only QCT probabilities are found to agree with the QM values. The good accordance found between the rigorous statistical models and the dynamical QM and QCT calculations for the O + HCl → ClO + H process underpins the assumption that the reaction pathway leading to ClO is predominantly governed by a complex-forming mechanism. In addition, to further test the statistical character of this reaction channel, the laboratory angular distribution and time-of-flight spectra obtained in a crossed molecular beam study by Balucani et al. [Chem. Phys. Lett. 1991, 180, 34] at a collision energy as high as 0.53 eV have been simulated using the state resolved differential cross section obtained with the statistical approaches yielding a satisfactory agreement with the experimental results. For the other channel, O + HCl → OH + Cl, noticeable differences between the statistical results and those found with the QCT calculation suggest that the dynamics of the reaction are controlled by a direct mechanism. The comparison between the QCT and QM-TDWP results in the whole range of collision energies lends credence to the QCT description of the dynamics of this reaction. © 2011 the Owner Societies.
Wed, 17 Oct 2012 10:06:35 GMThttp://hdl.handle.net/10261/582212012-10-17T10:06:35Z
- The O(1D) + H2 (X1Σ+, v, j) → OH(X2Π, v′, j′) + H(2S) reaction at low collision energy: When a simple statistical description of the dynamics workshttp://hdl.handle.net/10261/58254Title: The O(1D) + H2 (X1Σ+, v, j) → OH(X2Π, v′, j′) + H(2S) reaction at low collision energy: When a simple statistical description of the dynamics works
Authors: Rivero Santamaría, A.; González Martínez, M.L.; González-Lezana, Tomás; Rubayo-Soneira, Jesús; Bonnet, L.; Larregaray, P.
Abstract: In this communication, we highlight that statistical approaches for chemical reactions describe reasonably well the low energy dynamics of the title process. Consequently, such methods prove to be valuable to compute rate constants from low to room temperatures. Results are compared with experiment and recent precise quantum wave packet calculations [J. Phys. Chem. A, 2009, 113, 5285]. © 2011 the Owner Societies.
Wed, 17 Oct 2012 11:21:45 GMThttp://hdl.handle.net/10261/582542012-10-17T11:21:45Z
- Differential cross sections and product rotational polarization in A + BC reactions using wave packet methods: H+ D2 and Li + HF exampleshttp://hdl.handle.net/10261/20517Title: Differential cross sections and product rotational polarization in A + BC reactions using wave packet methods: H+ D2 and Li + HF examples
Authors: Zanchet, Alexandre; Roncero, Octavio; González-Lezana, Tomás; Rodríguez-López, A.; Aguado, Alfredo; Sanz, Cristina; Gómez Carrasco, Susana
Abstract: The state-to-state differential cross sections for some atom + diatom reactions have been calculated using a new wave packet code, MAD-WAVE3, which is described in some detail and uses either reactant or product Jacobi coordinates along the propagation. In order to show the accuracy and efficiency of the coordinate transformation required when using reactant Jacobi coordinates, as recently proposed [ J. Chem. Phys. 2006, 125, 054102], the method is first applied to the H + D2 reaction as a benchmark, for which exact time-independent calculations are also performed. It is found that the use of reactant coordinates yields accurate results, with a computational effort slightly lower than that when using product coordinates. The H+ + D2 reaction, with the same masses but a much deeper insertion well, is also studied and exhibits a completely different mechanism, a complex-forming one which can be treated by statistical methods. Due to the longer range of the potential, product Jacobi coordinates are more efficient in this case. Differential cross sections for individual final rotational states of the products are obtained based on exact dynamical calculations for some selected total angular momenta, combined with the random phase approximation to save the high computational time required to calculate all partial waves with very long propagations. The results obtained are in excellent agreement with available exact time-independent calculations. Finally, the method is applied to the Li + HF system for which reactant coordinates are very well suited, and quantum differential cross sections are not available. The results are compared with recent quasiclassical simulations and experimental results [ J. Chem. Phys. 2005, 122, 244304]. Furthermore, the polarization of the product angular momenta is also analyzed as a function of the scattering angle.
Description: 14 pages, 12 figures, 1 table.
Mon, 01 Feb 2010 11:10:48 GMThttp://hdl.handle.net/10261/205172010-02-01T11:10:48Z
- Comparative configurational study for He, Ne, and Ar trimershttp://hdl.handle.net/10261/21373Title: Comparative configurational study for He, Ne, and Ar trimers
Authors: González-Lezana, Tomás; Rubayo-Soneira, Jesús; Miret-Artés, Salvador
Abstract: Helium trimer bound states are calculated by means of a variational method described in terms of atom pair coordinates and distributed Gaussian basis functions for zero total angular momentum. To show the feasibility of this method, we also apply it to the calculation of the first vibrational levels of the Ar3 and Ne3 clusters. Special emphasis is made on the study of the possible Efimov behavior of the first excited state found in the 4He3 trimer. Geometrical configurations of the ground and first excited states of these rare gas trimers have been exhaustively studied owing to the proper symmetry of the coordinates chosen.
Description: 11 pages, 5 figures, 7 tables.
Fri, 19 Feb 2010 11:36:13 GMThttp://hdl.handle.net/10261/213732010-02-19T11:36:13Z
- A dynamical study of the O(1D)+HCl reactionhttp://hdl.handle.net/10261/71036Title: A dynamical study of the O(1D)+HCl reaction
Authors: Bargueño, Pedro; Jambrina, P. G.; Alvariño, José M.; Hernández, M. L.; Aoiz, F. Javier; Menéndez, M.; Verdasco, E.; Hankel, M.; Smith, S.C.; González-Lezana, Tomás
Description: International Meeting on Atomic and Molecular Physics and Chemistry, Madrid, June 29-July 2, 2010. http://fama.iff.csic.es/con/imampc-2010/
Mon, 04 Mar 2013 12:49:05 GMThttp://hdl.handle.net/10261/710362013-03-04T12:49:05Z
- Quantum mechanical study of the proton exchange in the ortho-para H 2 conversion reaction at low temperaturehttp://hdl.handle.net/10261/58226Title: Quantum mechanical study of the proton exchange in the ortho-para H 2 conversion reaction at low temperature
Authors: Honvault, Pascal; Jorfi, Mohamed; González-Lezana, Tomás; Faure, A.; Pagani, L.
Abstract: Ortho-para H2 conversion reactions mediated by the exchange of a H+ proton have been investigated at very low energy for the first time by means of a time independent quantum mechanical (TIQM) approach. State-to-state probabilities and cross sections for H+ + H 2 (v = 0, j = 0,1) processes have been calculated for a collision energy, Ec, ranging between 10-6 eV and 0.1 eV. Differential cross sections (DCSs) for H+ + H2 (v = 0, j = 1) → H+ + H2 (v′ = 0, j′ = 0) for very low energies only start to develop a proper global minimum around the sideways scattering direction ( ≈ 90°) at Ec = 10-3 eV. Rate coefficients, a crucial information required for astrophysical models, are provided between 10 K and 100 K. The relaxation ortho-para process j = 1 → j′ = 0 is found to be more efficient than the j = 0 → j′ = 1 conversion at low temperatures, in line with the extremely small ratio between the ortho and para species of molecular hydrogen predicted at the temperature of interstellar cold molecular clouds. The results obtained by means of a statistical quantum mechanical (SQM) model, which has previously proved to provide an adequate description of the dynamics of the title reactions at a higher collision energy regime, have been compared with the TIQM results. A reasonable good agreement has been found with the only exception of the DCSs for the H+ + H2 (v = 0, j = 1) → H+ + H 2 (v′ = 0, j′ = 0) process at very low energy. SQM cross sections are also slightly below the quantum results. Estimates for the rate coefficients, in good accord with the TIQM values, are a clear improvement with respect to pioneering statistical studies on the reaction. © the Owner Societies 2011.
Wed, 17 Oct 2012 10:22:57 GMThttp://hdl.handle.net/10261/582262012-10-17T10:22:57Z
- Examination of the Feynman–Hibbs approach in the study of NeN-coronene clusters at low temperatureshttp://hdl.handle.net/10261/131645Title: Examination of the Feynman–Hibbs approach in the study of NeN-coronene clusters at low temperatures
Authors: Rodríguez-Cantano, Rocío; Pérez de Tudela, Ricardo; Bartolomei, Massimiliano; Hernández, Marta I.; Campos-Martínez, José; González-Lezana, Tomás; Villarreal, Pablo; Hernández-Rojas, Javier; Bretón, José
Abstract: Feynman−Hibbs (FH) effective potentials constitute
an appealing approach for investigations of many-body
systems at thermal equilibrium since they allow us to easily
include quantum corrections within standard classical simulations.
In this work we apply the FH formulation to the study of
NeN-coronene clusters (N = 1−4, 14) in the 2−14 K
temperature range. Quadratic (FH2) and quartic (FH4)
contributions to the effective potentials are built upon Ne−Ne
and Ne-coronene analytical potentials. In particular, a new
corrected expression for the FH4 effective potential is reported.
FH2 and FH4 cluster energies and structuresobtained from
energy optimization through a basin-hopping algorithm as well
as classical Monte Carlo simulationsare reported and compared with reference path integral Monte Carlo calculations. For
temperatures T > 4 K, both FH2 and FH4 potentials are able to correct the purely classical calculations in a consistent way.
However, the FH approach fails at lower temperatures, especially the quartic correction. It is thus crucial to assess the range of
applicability of this formulation and, in particular, to apply the FH4 potentials with great caution. A simple model of N isotropic
harmonic oscillators allows us to propose a means of estimating the cutoff temperature for the validity of the method, which is
found to increase with the number of atoms adsorbed on the coronene molecule. © XXXX American Chemical Society
Description: 10 págs.; 7 figs.; 3 tabs.
http://hdl.handle.net/10261/131645
- Low energy complex-forming dynamics on atom-diatom reactionshttp://hdl.handle.net/10261/135517Title: Low energy complex-forming dynamics on atom-diatom reactions
Authors: González-Lezana, Tomás
Description: QRS XIII, Salamanca (Spain), July 6th to 10th, 2015; http://fama.iff.csic.es/con/QRS-2015
Fri, 12 Aug 2016 07:53:21 GMThttp://hdl.handle.net/10261/1355172016-08-12T07:53:21Z
- Low temperature dynamics of atom-diatom collisionshttp://hdl.handle.net/10261/135519Title: Low temperature dynamics of atom-diatom collisions
Authors: González-Lezana, Tomás
Description: Conferencia invitadas; QSCP 2015 Varna, Bulgaria, 14-20 September 2015; http://ntl.inrne.bas.bg/qscp2015/
Fri, 12 Aug 2016 08:11:31 GMThttp://hdl.handle.net/10261/1355192016-08-12T08:11:31Z
- Wave packet and statistical quantum calculations for the He + NeH+ ¿ HeH+ + Ne reaction on the ground electronic statehttp://hdl.handle.net/10261/135660Title: Wave packet and statistical quantum calculations for the He + NeH+ ¿ HeH+ + Ne reaction on the ground electronic state
Authors: Koner, Debasish; Barrios, Lizandra; González-Lezana, Tomás; Panda, Aditya N.
Description: QRS XIII, Salamanca (Spain), July 6th to 10th, 2015; http://fama.iff.csic.es/con/QRS-2015/
Fri, 19 Aug 2016 08:57:15 GMThttp://hdl.handle.net/10261/1356602016-08-19T08:57:15Z
- Theoretical investigations on doped rare gas clusters with atomic, diatomic and polyatomic impuritieshttp://hdl.handle.net/10261/152675Title: Theoretical investigations on doped rare gas clusters with atomic, diatomic and polyatomic impurities
Authors: Rodríguez-Cantano, Rocío; González-Lezana, Tomás; Villarreal, Pablo
Abstract: Helium clusters formed with up to N ~ 70 atoms doped with an impurity X have been studied by means of Monte Carlo (MC) simulations and classical optimization algorithms [1]. The size of the dopant under consideration ranges from atoms (Ca) [2,3],
diatoms (Rb2) [4-7] and extends to polycyclic aromatic hydrocarbons such as coronene (C_24H_12) [8]. Energetics and structure of the corresponding He_N-X systems has been analyzed for different temperature ranges with a path integral MC (PIMC) approach. A
variety of interaction potentials have been employed and the effect of their strength was studied in detail for He_N-Ca. Special emphasis is made on general issues such as the position of the impurity with respect to the helium cluster and the role of its internal
degrees of freedom such as rotation. The structure of the systems formed when helium atoms are adsorbed on the coronene
surface at T = 2 K have been investigated in detail [8]. Equilibrium energies and geometries are calculated and the possible competition between different rare gas atoms is analyzed.
Description: Conferencia invitada ; Mendoza, Argentina. 9th-13st of May 2016 ; http://photodynamics9.wixsite.com/phd9
Wed, 12 Jul 2017 10:46:37 GMThttp://hdl.handle.net/10261/1526752017-07-12T10:46:37Z
- Comparative investigation of pure and mixed rare gas atoms on coronene moleculeshttp://hdl.handle.net/10261/154934Title: Comparative investigation of pure and mixed rare gas atoms on coronene molecules
Authors: Rodríguez-Cantano, Rocío; Bartolomei, Massimiliano; Hernández, Marta I.; Campos-Martínez, José; González-Lezana, Tomás; Villarreal, Pablo; Pérez de Tudela, Ricardo; Pirani, Fernando; Hernández-Rojas, Javier; Bretón, José
Abstract: Clusters formed by the combination of rare gas (RG) atoms of He, Ne, Ar, and Kr on coronene have been investigated by means of a basin-hopping algorithm and path integral Monte Carlo calculations at T = 2 K. Energies and geometries have been obtained and the role played by the specific RG-RG and RG-coronene interactions on the final results is analysed in detail. Signatures of diffuse behavior of the He atoms on the surface of the coronene are in contrast with the localization of the heavier species, Ar and Kr. The observed coexistence of various geometries for Ne suggests the motion of the RG atoms on the multi-well potential energy surface landscape offered by the coronene. Therefore, the investigation of different clusters enables a comparative analysis of localized versus non-localized features. Mixed Ar-He-coronene clusters have also been considered and the competition of the RG atoms to occupy the docking sites on the molecule is discussed. All the obtained information is crucial to assess the behavior of coronene, a prototypical polycyclic aromatic hydrocarbon clustering with RG atoms at a temperature close to that of interstellar medium, which arises from the critical balance of the interactions involved. Published by AIP Publishing.
Description: 10 pags., 6 figs., 4 tabs.
Mon, 11 Sep 2017 07:55:17 GMThttp://hdl.handle.net/10261/1549342017-09-11T07:55:17Z
- State-to-State Dynamics of the Ne + HeH+ (v = 0, j = 0) → NeH+(v', j') + He Reactionhttp://hdl.handle.net/10261/145803Title: State-to-State Dynamics of the Ne + HeH+ (v = 0, j = 0) → NeH+(v', j') + He Reaction
Authors: Koner, Debasish; Barrios, Lizandra; González-Lezana, Tomás; Panda, Aditya N.
Abstract: The dynamics of the Ne + HeH(v = 0, j = 0) → NeH(v', j') + He reaction was analyzed in detail at the state-to-state level. A time-independent quantum mechanical (TIQM) method was applied to calculate rovibrational distributions and differential cross sections (DCSs), in comparison with quasi-classical trajectory and statistical quantum predictions. Possible changes in the dynamical mechanisms that define the process were also investigated as a function of the collision energy. At the lowest energy regime, the TIQM results produce a noticeably different cross section in comparison with previously reported time-dependent wave packet results. Although the statistical methods reproduce some dynamical features, especially as the energy increases, the marked preference for the forward scattering direction on the DCSs suggests that the reaction mainly follows a direct mechanism. © 2016 American Chemical Society
Description: 11 págs.; 11 figs.; 2 tabs.
Tue, 28 Feb 2017 07:50:11 GMThttp://hdl.handle.net/10261/1458032017-02-28T07:50:11Z
- Erratum: >A comparative study of the Si+O2\SiO+O reaction dynamics from quasiclassical trajectory and statistical based methods> [J. Chem. Phys. 128, 174307 (2008)]http://hdl.handle.net/10261/93798Title: Erratum: >A comparative study of the Si+O2\SiO+O reaction dynamics from quasiclassical trajectory and statistical based methods> [J. Chem. Phys. 128, 174307 (2008)]
Authors: Dayou, F.; Larregaray, Pascal; Bonnet, L.; Rayez, J.C.; Arenas, P.N.; González-Lezana, Tomás
Tue, 18 Mar 2014 10:15:57 GMThttp://hdl.handle.net/10261/937982014-03-18T10:15:57Z
- Dynamics of atom-diatom reactions at the low energy regimehttp://hdl.handle.net/10261/114440Title: Dynamics of atom-diatom reactions at the low energy regime
Authors: González-Lezana, Tomás
Abstract: The dynamics of some atom-diatom reactions has been investigated in the low collision energy regime (Ecoll < 10^-1 eV). The possibility of complex-forming mechanisms is analyzed by means of a statistical quantum method in comparison with quantum mechanical results and experimental measurements. The case of the H^+ + H_2 reaction, and isotopic variants, for which a significant dependence on the energy range has been reported before, is treated in detail. Recent studies on the D^+ + H_2 reaction found theoretical rate coefficients in a good agreement with experiment down to 10^-3 eV . Similar investigations in other reactions such as Li+YbLi and He+NeH^+ are discussed.
Description: The 8th International Meeting on Photodynamics and Related Aspects, Oaxaca, México, Oct 26-31, 2014. Conferencia invitada
Wed, 29 Apr 2015 09:41:31 GMThttp://hdl.handle.net/10261/1144402015-04-29T09:41:31Z
- The dynamics of the C+OH and the H3+ reactionshttp://hdl.handle.net/10261/88104Title: The dynamics of the C+OH and the H3+ reactions
Authors: González-Lezana, Tomás
Description: Understanding chemical reactivity: from modeling to experiments, Quantum Days in Bilbao July 23-24 (2012)
Tue, 03 Dec 2013 12:17:29 GMThttp://hdl.handle.net/10261/881042013-12-03T12:17:29Z
- A study on the dynamics of two atom-diatom reactions: O(1D)+HCl and H^+ + H_2http://hdl.handle.net/10261/88754Title: A study on the dynamics of two atom-diatom reactions: O(1D)+HCl and H^+ + H_2
Authors: González-Lezana, Tomás
Description: International Meeting on Atomic and Molecular Physics and Chemistry, Rennes, (France), 5-8 July 2011.
Tue, 17 Dec 2013 12:16:34 GMThttp://hdl.handle.net/10261/887542013-12-17T12:16:34Z
- H2, H 3 + and the age of molecular clouds and prestellar coreshttp://hdl.handle.net/10261/65563Title: H2, H 3 + and the age of molecular clouds and prestellar cores
Authors: Pagani, L.; Lesaffre, P.; Roueff, E.; Jorfi, Mohamed; Honvault, Pascal; González-Lezana, Tomás; Fauré, A.
Abstract: Measuring the age of molecular clouds and prestellar cores is a difficult task that has not yet been successfully accomplished although the information is of paramount importance to help in understanding and discriminating between different formation scenarios. Most chemical clocks suffer from unknown initial conditions and are therefore difficult to use. We propose a new approach based on a subset of deuterium chemistry that takes place in the gas phase and for which initial conditions are relatively well known. It relies primarily on the conversion of H 3 + into H 2D + to initiate deuterium enrichment of the molecular gas. This conversion is controlled by the ortho/para ratio of H2 that is thought to be produced with the statistical ratio of 3 and subsequently slowly decays to an almost pure para-H2 phase. This slow decay takes approximately 1 Myr and allows us to set an upper limit on the age of molecular clouds. The deuterium enrichment of the core takes longer to reach equilibrium and allows us to estimate the time necessary to form a dense prestellar core, i.e. the last step before the collapse of the core into a protostar. We find that the observed abundance and distribution of DCO + and N 2D + argue against quasi-static core formation and favour dynamical formation on time scales of less than 1 Myr. Another consequence is that ortho-H 2 remains comparable to para-H 2 in abundance outside the dense cores. © 2012 The Royal Society.
Thu, 31 Jan 2013 12:26:11 GMThttp://hdl.handle.net/10261/655632013-01-31T12:26:11Z
- Investigating transition state resonances in the time domain by means of Bohmian mechanics: The F + HD reactionhttp://hdl.handle.net/10261/65234Title: Investigating transition state resonances in the time domain by means of Bohmian mechanics: The F + HD reaction
Authors: Sanz, Ángel S.; López Durán, David; González-Lezana, Tomás
Abstract: In this work, we investigate the existence of transition state resonances on atom¿diatom reactive collisions from a time-dependent perspective, stressing the role of quantum trajectories as a tool to analyze this phenomenon. As it is shown, when one focusses on the quantum probability current density, new dynamical information about the reactive process can be extracted. In order to detect the effects of the different rotational populations and their dynamics/coherences, we have considered a reduced twodimensional dynamics obtained from the evolution of a full three-dimensional quantum time-dependent wave packet associated with a particular angle. This reduction procedure provides us with information about the entanglement between the radial degrees of freedom (r,R) and the angular one (c), which can be considered as describing an environment. The combined approach here proposed has been applied to study the F + HD reaction, for which the FH + D product channel exhibits a resonance-mediated dynamics.
Mon, 28 Jan 2013 10:45:33 GMThttp://hdl.handle.net/10261/652342013-01-28T10:45:33Z
- Wave packet and statistical quantum calculations for the He + NeH+ ¿ HeH+ + Ne reaction on the ground electronic statehttp://hdl.handle.net/10261/114244Title: Wave packet and statistical quantum calculations for the He + NeH+ ¿ HeH+ + Ne reaction on the ground electronic state
Authors: Koner, Debasish; Barrios, Lizandra; González-Lezana, Tomás; Panda, Aditya N.
Abstract: © 2014 AIP Publishing LLC. A real wave packet based time-dependent method and a statistical quantum method have been used to study the He + NeH+ (v, j) reaction with the reactant in various ro-vibrational states, on a recently calculated ab initio ground state potential energy surface. Both the wave packet and statistical quantum calculations were carried out within the centrifugal sudden approximation as well as using the exact Hamiltonian. Quantum reaction probabilities exhibit dense oscillatory pattern for smaller total angular momentum values, which is a signature of resonances in a complex forming mechanism for the title reaction. Significant differences, found between exact and approximate quantum reaction cross sections, highlight the importance of inclusion of Coriolis coupling in the calculations. Statistical results are in fairly good agreement with the exact quantum results, for ground ro-vibrational states of the reactant. Vibrational excitation greatly enhances the reaction cross sections, whereas rotational excitation has relatively small effect on the reaction. The nature of the reaction cross section curves is dependent on the initial vibrational state of the reactant and is typical of a late barrier type potential energy profile.
Description: 11 pags.; 9 figs.; 1 tab.
Mon, 27 Apr 2015 09:58:23 GMThttp://hdl.handle.net/10261/1142442015-04-27T09:58:23Z
- Coronene molecules in helium clusters: Quantum and classical studies of energies and configurationshttp://hdl.handle.net/10261/126691Title: Coronene molecules in helium clusters: Quantum and classical studies of energies and configurations
Authors: Rodríguez-Cantano, Rocío; Pérez de Tudela, Ricardo; Bartolomei, Massimiliano; Hernández, Marta I.; Campos-Martínez, José; González-Lezana, Tomás; Villarreal, Pablo; Hernández-Rojas, Javier; Bretón, José
Abstract: Coronene-doped helium clusters have been studied by means of classical and quantum mechanical (QM) methods using a recently developed He–C24H12 global potential based on the use of optimized atom-bond improved Lennard-Jones functions. Equilibrium energies and geometries at global and local minima for systems with up to 69 He atoms were calculated by means of an evolutive algorithm and a basin-hopping approach and compared with results from path integral Monte Carlo (PIMC) calculations at 2 K. A detailed analysis performed for the smallest sizes shows that the precise localization of the He atoms forming the first solvation layer over the molecular substrate is affected by differences between relative potential minima. The comparison of the PIMC results with the predictions from the classical approaches and with diffusion Monte Carlo results allows to examine the importance of both the QM and thermal effects.
Description: Under the terms of the Creative Commons Attribution (CC BY) license to their work.
http://hdl.handle.net/10261/126691
- Dinámica Cuántica y Tratamientos Estadísticos en Reacciones Oxigenadas de Capa Abierta: O(3P, 1D)+HCl, H+O2 y O(3P)+OHhttp://hdl.handle.net/10261/90678Title: Dinámica Cuántica y Tratamientos Estadísticos en Reacciones Oxigenadas de Capa Abierta: O(3P, 1D)+HCl, H+O2 y O(3P)+OH
Authors: Bargueño, Pedro; Alvariño Herrero, José María; González-Lezana, Tomás
Tue, 11 Feb 2014 10:56:12 GMThttp://hdl.handle.net/10261/906782014-02-11T10:56:12Z
- Influence of rotation and isotope effects on the dynamics of the N ( 2D) + H2 reactive system and of its deuterated variantshttp://hdl.handle.net/10261/75040Title: Influence of rotation and isotope effects on the dynamics of the N ( 2D) + H2 reactive system and of its deuterated variants
Authors: Bañares, Luis; Aoiz, F. Javier; González-Lezana, Tomás; Herrero, Víctor J.; Tanarro, Isabel
Abstract: Integral cross sections and thermal rate constants have been calculated for the N 2D +H2 reaction and its isotopic variants N 2D +D2 and the two-channel N 2D +HD by means of quasiclassical trajectory and statistical quantum-mechanical model methods on the latest ab initio potential-energy surface T.-S. Ho et al., J. Chem. Phys. 119, 3063 2003 . The effect of rotational excitation of the
diatom on the dynamics of these reactions has been investigated and interesting discrepancies between the classical and statistical model calculations have been found. Whereas a net effect of reagent rotation on reactivity is always observed in the classical calculations, only a very slight effect is observed in the case of the asymmetric N 2D +HD reaction for the statistical quantum-mechanical method. The thermal rate constants calculated on this Potential-Energy Surface using quasiclassical trajectory and statistical model methods are in good agreement with the experimental determinations, although the latter are somewhat larger. A reevaluation of the collinear barrier of the potential surface used in the present study seems timely. Further theoretical and experimental studies are needed for a full understanding of the dynamics of the title reaction. © 2005 American Institute of Physics.
Description: 9 p.: gráf.
Wed, 24 Apr 2013 11:39:05 GMThttp://hdl.handle.net/10261/750402013-04-24T11:39:05Z
- The reaction dynamics of H3+ at low enery regimeshttp://hdl.handle.net/10261/89590Title: The reaction dynamics of H3+ at low enery regimes
Authors: González-Lezana, Tomás; Scribano Yohann; Honvault, Pascal
Fri, 17 Jan 2014 11:28:22 GMThttp://hdl.handle.net/10261/895902014-01-17T11:28:22Z
- Quantum dynamics study of the D+ + H2 reaction at low temperaturehttp://hdl.handle.net/10261/89581Title: Quantum dynamics study of the D+ + H2 reaction at low temperature
Authors: Scribano Yohann; Honvault, Pascal; González-Lezana, Tomás
Fri, 17 Jan 2014 10:14:56 GMThttp://hdl.handle.net/10261/895812014-01-17T10:14:56Z
- A comparison of quantum and quasiclassical statistical models for reactions of electronically excited atoms with molecular hydrogenhttp://hdl.handle.net/10261/79386Title: A comparison of quantum and quasiclassical statistical models for reactions of electronically excited atoms with molecular hydrogen
Authors: Aoiz, F. Javier; González-Lezana, Tomás; Sáez Rábanos, V.
Abstract: A detailed comparison of statistical models based on the quasiclassical trajectory SQCT and
quantum mechanical SQM methods is presented in this work for the C
1
D +H2
, S
1
D +H2
,
O
1
D +H2
and N
2
D +H2
insertion reactions. Reaction probabilities, integral ICS and differential
DCS cross sections at different levels of product’s state resolution are shown and discussed for
these reactions. The agreement is in most cases excellent and indicates that the effect of tunneling
through the centrifugal barrier is negligible. However, if there exists a dynamical barrier, as in the
case of the N
2
D +H2
reaction, some of the SQM results can be slightly different than those
calculated with the SQCT model. The rationale of the observed similarities and discrepancies can be
traced back to the speciﬁc topologies of the potential energy surfaces for each of the reactions
examined. The SQCT model is sensitive enough to show the relatively small inaccuracies resulting
from the decoupling inherent to the centrifugal sudden approximation when used in the SQM
calculations. In addition, the effect of ignoring the parity conservation is also examined. This effect
is in general minor except in particular cases such as the DCS from initial rotational state j=0,
which requires, in order to reproduce the sharp forward and backward peaks, the explicit
conservation of parity. © 2008 American Institute of Physics
Description: 12 pags. ; 13 figs.
Thu, 11 Jul 2013 07:41:59 GMThttp://hdl.handle.net/10261/793862013-07-11T07:41:59Z
- A comparative study of the Si+O2→SiO+O reaction dynamics from quasiclassical trajectory and statistical based methodshttp://hdl.handle.net/10261/79347Title: A comparative study of the Si+O2→SiO+O reaction dynamics from quasiclassical trajectory and statistical based methods
Authors: Dayou, F.; Larregaray, Pascal; Bonnet, L.; Rayez, J.C.; Arenas, P.N.; González-Lezana, Tomás
Abstract: The dynamics of the singlet channel of the Si+O2→SiO+O reaction is investigated by means of quasiclassical trajectory (QCT) calculations and two statistical based methods, the statistical quantum method (SQM) and a semiclassical version of phase space theory (PST). The dynamics calculations have been performed on the ground 1A′ potential energy surface of Dayou and Spielfiedel [J. Chem. Phys. 119, 4237 (2003)] for a wide range of collision energies (Ec = 5–400 meV) and initial O2 rotational states (j = 1–13). The overall dynamics is found to be highly sensitive to the selected initial conditions of the reaction, the increase in either the collisional energy or the O2 rotational excitation giving rise to a continuous transition from a direct abstraction mechanism to an indirect insertion mechanism. The product state properties associated with a given collision energy of 135 meV and low rotational excitation of O2 are found to be consistent with the inverted SiO vibrational state distribution observed in a recent experiment. The SQM and PST statistical approaches, especially designed to deal with complex-forming reactions, provide an accurate description of the QCT total integral cross sections and opacity functions for all cases studied. The ability of such statistical treatments in providing reliable product state properties for a reaction dominated by a competition between abstraction and insertion pathways is carefully examined, and it is shown that a valuable information can be extracted over a wide range of selected initial conditions.
© 2008 American Institute of Physics
Description: 17 pags. ; 11 figs. Erratum: “A comparative study of the Si+O2SiO+O reaction dynamics from quasiclassical trajectory and statistical based methods” [J. Chem. Phys. 128, 174307 (2008)]
Fabrice Dayou et al.
J. Chem. Phys. 130, 049901 (2009)
Wed, 10 Jul 2013 11:04:37 GMThttp://hdl.handle.net/10261/793472013-07-10T11:04:37Z
- Complex-forming dynamics on atom-diatom reactions: O(1D)+HCl and H^+_3http://hdl.handle.net/10261/88812Title: Complex-forming dynamics on atom-diatom reactions: O(1D)+HCl and H^+_3
Authors: González-Lezana, Tomás
Wed, 18 Dec 2013 12:53:19 GMThttp://hdl.handle.net/10261/888122013-12-18T12:53:19Z
- The dynamics behind atom-diatom collisions with competing reaction pathwayshttp://hdl.handle.net/10261/88098Title: The dynamics behind atom-diatom collisions with competing reaction pathways
Authors: González-Lezana, Tomás
Tue, 03 Dec 2013 12:00:23 GMThttp://hdl.handle.net/10261/880982013-12-03T12:00:23Z
- The dynamics of the H3+ reactionhttp://hdl.handle.net/10261/89589Title: The dynamics of the H3+ reaction
Authors: González-Lezana, Tomás
Fri, 17 Jan 2014 11:19:11 GMThttp://hdl.handle.net/10261/895892014-01-17T11:19:11Z
- Ultracold chemistry with alkali-metal-rare-earth moleculeshttp://hdl.handle.net/10261/130499Title: Ultracold chemistry with alkali-metal-rare-earth molecules
Authors: Makrides, C.; Hazra, J.; Pradhan, G.B.; Petrov, A.; Kendrick, B.K.; González-Lezana, Tomás; Balakrishnan, N.; Kotochigova, S.
Abstract: © 2015 American Physical Society. A first principles study of the dynamics of Li6(2S)+Li6Yb174(2Σ+)→6Li2(1Σ+)+Yb174(1S) reaction is presented at cold and ultracold temperatures. The computations involve determination and analytic fitting of a three-dimensional potential energy surface for the Li2Yb system and quantum dynamics calculations of varying complexities, ranging from exact quantum dynamics within the close-coupling scheme, to statistical quantum treatment, and universal models. It is demonstrated that the two simplified methods yield zero-temperature limiting reaction rate coefficients in reasonable agreement with the full close-coupling calculations. The effect of the three-body term in the interaction potential is explored by comparing quantum dynamics results from a pairwise potential that neglects the three-body term to that derived from the full interaction potential. Inclusion of the three-body term in the close-coupling calculations was found to reduce the limiting rate coefficients by a factor of two. The reaction exoergicity populates vibrational levels as high as v=19 of the Li62 molecule in the limit of zero collision energy. Product vibrational distributions from the close-coupling calculations reveal sensitivity to inclusion of three-body forces in the interaction potential. Overall, the results indicate that a simplified model based on the long-range potential is able to yield reliable values of the total reaction rate coefficient in the ultracold limit but a more rigorous approach based on statistical quantum or quantum close-coupling methods is desirable when product rovibrational distribution is required.
Description: 12 págs.; 9 figs.; tab.; PACS number(s): 34.50.Cx, 34.50.Lf, 82.20.Xr
http://hdl.handle.net/10261/130499
- Capture approximations beyond a statistical quantum mechanical method for atom-diatom reactionshttp://hdl.handle.net/10261/143840Title: Capture approximations beyond a statistical quantum mechanical method for atom-diatom reactions
Authors: Barrios, Lizandra; Rubayo-Soneira, Jesús; González-Lezana, Tomás
Abstract: Statistical techniques constitute useful approaches to investigate atom-diatom reactions mediated by insertion dynamics which involves complex-forming mechanisms. Different capture schemes based on energy considerations regarding the specific diatom rovibrational states are suggested to evaluate the corresponding probabilities of formation of such collision species between reactants and products in an attempt to test reliable alternatives for computationally demanding processes. These approximations are tested in combination with a statistical quantum mechanical method for the S + H_2(v = 0,j = 1) ->SH + H and Si + O_2(v = 0,j = 1) ¿ SiO + O reactions, where this dynamical mechanism plays a significant role, in order to probe their validity. © EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2016
Description: 7 págs.; 6 figs.; 1 tab.
Mon, 13 Feb 2017 10:38:00 GMThttp://hdl.handle.net/10261/1438402017-02-13T10:38:00Z
- Scattering study of the Ne + NeH^+(v0 = 0, j0 = 0) -> NeH^+ + Ne reaction on an ab initio based analytical potential energy surfacehttp://hdl.handle.net/10261/145772Title: Scattering study of the Ne + NeH^+(v0 = 0, j0 = 0) -> NeH^+ + Ne reaction on an ab initio based analytical potential energy surface
Authors: Koner, Debasish; Barrios, Lizandra; González-Lezana, Tomás; Panda, Aditya N.
Abstract: Initial state selected dynamics of the Ne + NeH+(v0 = 0, j0 = 0) ¿ NeH+ + Ne reaction is investigated by quantum and statistical quantum mechanical (SQM) methods on the ground electronic state. The three-body ab initio energies on a set of suitably chosen grid points have been computed at CCSD(T)/aug-cc-PVQZ level and analytically fitted. The fitting of the diatomic potentials, computed at the same level of theory, is performed by spline interpolation. A collinear [NeHNe]+ structure lying 0.72 eV below the Ne + NeH+ asymptote is found to be the most stable geometry for this system. Energies of low lying vibrational states have been computed for this stable complex. Reaction probabilities obtained from quantum calculations exhibit dense oscillatory structures, particularly in the low energy region and these get partially washed out in the integral cross section results. SQM predictions are devoid of oscillatory structures and remain close to 0.5 after the rise at the threshold thus giving a crude average description of the quantum probabilities. Statistical cross sections and rate constants are nevertheless in sufficiently good agreement with the quantum results to suggest an important role of a complex-forming dynamics for the title reaction. ©2016 AIP Publishing
Description: 11 págs.; 7 figs.; 4 tabs.
Mon, 27 Feb 2017 10:33:53 GMThttp://hdl.handle.net/10261/1457722017-02-27T10:33:53Z
- The H^+ + H_2http://hdl.handle.net/10261/114197Title: The H^+ + H_2
Authors: González-Lezana, Tomás; Honvault, Pascal
Abstract: H3+ plays a crucial role in Astrophysics, taking part in the early chemistry responsible for the formation of the stars. It is also one of the most abundant ionic species in hydrogen plasmas. The spectroscopy of the system has been the subject of intensive work in the past. Association processes to form and dissociative recombination with electrons have also been investigated in detail in order to understand the observed abundance of the molecule in the interstellar medium. Besides all these questions, in this work, we review some of the most relevant aspects regarding the dynamics of the H+¿+¿H2 reaction and its isotopic variants. A discussion on the most commonly found numerical difficulties in the theoretical study of this reactive collision is included. © 2014 Taylor & Francis
Description: 25 pags.; 5 figs.
Mon, 27 Apr 2015 07:57:51 GMThttp://hdl.handle.net/10261/1141972015-04-27T07:57:51Z
- Theoretical investigations on doped rare gas clusters with neutral or ionic atomic and diatomic impuritieshttp://hdl.handle.net/10261/152539Title: Theoretical investigations on doped rare gas clusters with neutral or ionic atomic and diatomic impurities
Authors: Rodríguez-Cantano, Rocío; González-Lezana, Tomás; Villarreal, Pablo
Abstract: Helium clusters formed with up to N ~ 70 atoms doped with an impurity X have been
studied by means of Monte Carlo (MC) simulations and classical optimization
algorithms [1]. The dopants under consideration are neutral atoms (Ca) [2,3] and
diatoms (Rb2) [4-7], and anionic species He*- and He2 *-[8]. Energetics and structure
of the corresponding HeN-X systems has been analyzed for different temperature ranges
with a path integral MC (PIMC) approach. A variety of interaction potentials have been
employed and the effect of their strength was studied in detail. Special emphasis is
made on general issues such as the position of the impurity with respect to the helium
cluster and the role of its internal degrees of freedom such as rotation.
Description: MOLEC 2016, Toledo (Spain), 11 - 16 September 2016
Mon, 10 Jul 2017 10:12:18 GMThttp://hdl.handle.net/10261/1525392017-07-10T10:12:18Z
- Path integral Monte Carlo investigations on doped helium clustershttp://hdl.handle.net/10261/145680Title: Path integral Monte Carlo investigations on doped helium clusters
Authors: Rodríguez-Cantano, Rocío; González-Lezana, Tomás; Villarreal, Pablo
Abstract: One of the most commonly employed methods to study doped helium clusters is the path integral Monte Carlo (PIMC) approach. In this review we present results of recent investigations on a series of both atomic and diatomic dopants attached to droplets formed with up to 40 He atoms. Besides the comparison with similar studies existing in the literature, this work also gives the possibility to analyse different issues such as the role played by the He¿impurity interaction in the overall geometry of the clusters, the inclusion of internal molecular degrees of freedom and the exchange permutation symmetry in the PIMC calculations. The study of the structure and energies of and at thermal equilibrium presented in this work thus covers most of the usual aspects treated for these kinds of doped systems. © 2016 Taylor & Francis Group
Description: 32 págs.; 21 figs.; 5 tabs.
Fri, 24 Feb 2017 07:12:24 GMThttp://hdl.handle.net/10261/1456802017-02-24T07:12:24Z
- A configurational study of helium clusters doped with He∗− and He2 ∗−http://hdl.handle.net/10261/128098Title: A configurational study of helium clusters doped with He∗− and He2 ∗−
Authors: Rodríguez-Cantano, Rocío; González-Lezana, Tomás; Villarreal, Pablo; Gianturco, Franco A.
Abstract: Helium clusters doped with electronically excited atomic and molecular helium anions He∗− and He∗−
2 at T = 0.4 K are studied by means of path integral Monte Carlo calculations. Geometry and energetics
of the systems with up to 32 solvating He atoms are characterised. The interactions between the
anions and the neutral He atoms have been described by fitting previously reported ab initio points to
analytical expressions. The HeN–He∗− clusters with N > 6 display a structure defined by a bipyramid
which completely solvates the atomic anion, whereas the rest of surrounding He atoms form a dimple
around that initial cage. On the contrary, the structures observed for the HeN–He∗−2 clusters clearly
show the dopant located outside the helium droplet, thereby confirming the heliophobic character of
He∗− 2. C 2015 AIP Publishing LLC
Description: 9 pags.; 10 figs.; 4 tabs.
http://hdl.handle.net/10261/128098
- Reactive collisions of ultracold polar molecules and atomshttp://hdl.handle.net/10261/89586Title: Reactive collisions of ultracold polar molecules and atoms
Authors: González-Lezana, Tomás; Makrides, C.; Kotochigova, S.
Description: Quantum Reactive Scattering 2013 (12th edition), Bordeaux (France), June 10-14 2013. http://web.ism.u-bordeaux1.fr/qrs12/index.php
Fri, 17 Jan 2014 11:04:55 GMThttp://hdl.handle.net/10261/895862014-01-17T11:04:55Z
- Effects of the rotational excitation of D2 and of the potential energy surface on the H+ + D2 →hD+ D+ reactionhttp://hdl.handle.net/10261/93654Title: Effects of the rotational excitation of D2 and of the potential energy surface on the H+ + D2 →hD+ D+ reaction
Authors: González-Lezana, Tomás; Honvault, Pascal; Jambrina, P.G.; Aoiz, F. Javier; Launay, Jean-Michel
Abstract: The H+ + D2 →HD+ D+ reaction has been theoretically investigated by means of an exact quantum mechanical approach, a quasiclassical trajectory method, and two statistical methods based in the propagation of either wave functions or trajectories. The study addresses the possible changes on the overall dynamics of the title reaction when the D 2 diatom is rotationally excited to its v=0, j=1 state. In addition, the reactivity for the ground rotational state on two different potential energy surfaces (PESs), namely, the surface by Aguado [J. Chem. Phys. 112, 1240 (2000)] and the PES by Kamisaka [J. Chem. Phys. 116, 654 (2002)], is examined. Reaction probabilities and cross sections at 0.524 and 0.1 eV collision energies are calculated. The major differences with respect to the reaction initiated with D2 in its ground rovibrational state are observed for the lowest collision energy Ec =0.1 eV. Differential cross sections have been found to depend to some extend on the PES employed. In addition, at E c =0.1 eV further discrepancies in the total and rotational cross sections are noticeable. © 2009 American Institute of Physics.
Fri, 14 Mar 2014 10:53:43 GMThttp://hdl.handle.net/10261/936542014-03-14T10:53:43Z
- Application of the stabilization method to interacting resonanceshttp://hdl.handle.net/10261/80932Title: Application of the stabilization method to interacting resonances
Authors: González-Lezana, Tomás; Delgado Barrio, Gerardo; Villarreal, Pablo; Gadéa, F.X.
Abstract: The stabilization method is applied to the case of interacting resonances in the photo-dissociation of van der Waals clusters composed by a rare gas atom bound to a dihalogen molecule. The study of an illustrative two-dimensional model consisting in a T-shaped NeI2 molecule shows the adequacy of the method whenever the projection of the stabilization wave functions on the assumed prepared initial state is accounted for. The agreement of the fragmentation cross-sections with some previous results using the effective resolvent method and accurate close-coupling calculations is excellent. The method reveals its utility as a complementary tool since allows, through the analysis of the stabilization wave function in terms of zero-order levels, a precise characterization of the resonant states involved.
Fri, 23 Aug 2013 08:18:06 GMThttp://hdl.handle.net/10261/809322013-08-23T08:18:06Z
- Photo-predissociation of the 4He 79Br2 complex: From empirical to ab initio potential energy surfaceshttp://hdl.handle.net/10261/108696Title: Photo-predissociation of the 4He 79Br2 complex: From empirical to ab initio potential energy surfaces
Authors: Hernández, Marta I.; González-Lezana, Tomás; Buchachenko, Alexei A.; Prosmiti, Rita; Lara Castells, María Pilar de; Delgado Barrio, Gerardo; Villarreal, Pablo
Mon, 15 Dec 2014 09:00:15 GMThttp://hdl.handle.net/10261/1086962014-12-15T09:00:15Z
- Reactive scattering 87Rb + 87RbHe→Rb2(3∑+u , v) + Heat ultra-low energieshttp://hdl.handle.net/10261/135600Title: Reactive scattering 87Rb + 87RbHe→Rb2(3∑+u , v) + Heat ultra-low energies
Authors: Villarreal, Pablo; Rodríguez-Cantano, Rocío; González-Lezana, Tomás; Prosmiti, Rita; Delgado Barrio, Gerardo; Jellinek, J.
Description: Conferencia invitada; Cost Action - MOLIM Molecules in Motions CM 1405, Université Paris Est - Marne la Vallée, August 27 - 29, 2015; http://cost-molim.eu
Wed, 17 Aug 2016 09:57:58 GMThttp://hdl.handle.net/10261/1356002016-08-17T09:57:58Z
- Quantum features of anionic species He*− and He2*− in small HeN clustershttp://hdl.handle.net/10261/130497Title: Quantum features of anionic species He*− and He2*− in small HeN clusters
Authors: Villarreal, Pablo; Rodríguez-Cantano, Rocío; González-Lezana, Tomás; Prosmiti, Rita; Delgado Barrio, Gerardo; Gianturco, Franco A.
Abstract: We present variational calculations on systems containing a few boson helium atoms attached to electronically excited atomic and molecular helium anions He*– and He2*– and characterize their structures and energetics. Previously reported high-level ab initio results [Huber, S. E.; Mauracher, A. Mol. Phys. 2014, 112, 794] to describe the interactions between excited (metastable) anions and a neutral He atom have been employed. For the case of the atomic species He*–, the corresponding interaction with He suggests large anharmonicity effects due to the presence of a deep well of ∼17 500 cm–1 at short distances, together with a more external shallow secondary well of ∼4 cm–1, both supporting bound levels. Moreover, when a sum of pairwise interactions is assumed to describe the full PES corresponding to the presence of several neutral He atoms, geometrical constraints already predict the complete solvation of the anionic impurity by six helium atoms, giving rise to a bipyramidal structure. In turn, for the anisotropic weak interaction He–He2*–, where the anionic dimer is considered as a rigid rotor, the obtained structures show the tendency of the helium atoms to pack themselves together and largely far away from the dopant, thereby confirming the heliophobic character of He2*–.
Tue, 29 Mar 2016 09:24:07 GMThttp://hdl.handle.net/10261/1304972016-03-29T09:24:07Z
- The weakly bound ground state of the LiHe_2 triatomic systemhttp://hdl.handle.net/10261/76659Title: The weakly bound ground state of the LiHe_2 triatomic system
Authors: Baccarelli, Isabella; Delgado Barrio, Gerardo; Gianturco, Franco Antonio; González-Lezana, Tomás; Miret-Artés, Salvador; Villarreal, Pablo
Abstract: We confirm the existence of and study the location and spatial shape for the ground bound state of the triatomic system that contains one lithium (6Li or 7Li) atom and two boson helium partners. The computational method employed involves a variationally determined multi-center expansion over Gaussian functions of variable width, as discussed in our previous recent work. The overall behavior of this very diffuse, bound wave-function with zero angular momentum is analyzed in detail to extract specific indicators on its spatial features. The strength of the available three-particle interaction is arbitrarily scaled in order to investigate the possible appearance of either halo or Efimov states in the present system.
Thu, 23 May 2013 12:05:57 GMThttp://hdl.handle.net/10261/766592013-05-23T12:05:57Z
- Vibrational and rotational bound states in floppy triatomic systems: The distributed Gaussian functions approachhttp://hdl.handle.net/10261/14440Title: Vibrational and rotational bound states in floppy triatomic systems: The distributed Gaussian functions approach
Authors: Baccarelli, Isabella; Gianturco, Franco Antonio; González-Lezana, Tomás; Delgado Barrio, Gerardo; Miret-Artés, Salvador; Villarreal, Pablo
Abstract: A variational method based on the use of bond coordinates and of a basis set expansion described by distributed Gaussian functions (DGF) is reviewed for its applications to the study of weakly bound triatomic clusters. This approach will be shown to be particularly well suited to treat very diffuse states as those presented by Noble gas (Ng) containing systems like the Ng3, and Ng2X, with X being also a very weakly bound atomic impurity. Several statistical properties such as radial distributions, sizes and dominance of triangular configurations for the corresponding bound states are shown to be directly obtained with this method over the whole spectrum of the floppy cluster bound states, in both the rotationless case and also when special care is taken to define rotational constants to yield rovibrational states and their energy levels.
Description: 32 pages, 12 figures, 2 tables.-- PACS nrs.: 03.65.Ge; 21.45.-v; 21.60.Gx; 36.40.-c.-- Printed version published Oct 2007.
Tue, 07 Jul 2009 09:16:49 GMThttp://hdl.handle.net/10261/144402009-07-07T09:16:49Z
- Quantum features of a barely bound molecular dopant: Cs2( 3Σu) in bosonic helium droplets of variable sizehttp://hdl.handle.net/10261/58299Title: Quantum features of a barely bound molecular dopant: Cs2( 3Σu) in bosonic helium droplets of variable size
Authors: Pérez de Tudela, Ricardo; López Durán, David; González-Lezana, Tomás; Delgado Barrio, Gerardo; Villarreal, Pablo; Gianturco, Franco Antonio; Yurtsever, Ersin
Abstract: We present in this work the study of small 4He N-Cs2(3Σu) aggregates (2 ≥ N ≥ 30) through combined variational, diffusion Monte Carlo (DMC), and path integral Monte Carlo (PIMC) calculations. The full surface is modeled as an addition of He-Cs2 interactions and He-He potentials. Given the negligible strength and large range of the He-Cs2 interaction as compared with the one for He-He, a propensity of the helium atoms to pack themselves together, leaving outside the molecular dopant is to be expected. DMC calculations determine the onset of helium gathering at N = 3. To analyze energetic and structural properties as a function of N, PIMC calculations with no bosonic exchange, i.e., Boltzmann statistics, at low temperatures are carried out. At T = 0.1 K, although acceptable one-particle He-Cs2 distributions are obtained, two-particle He-He distributions are not well described, indicating that the proper symmetry should be taken into account. PIMC distributions at T = 1 K already compare well with DMC ones and show minor exchange effects, although binding energies are still far from having converged in terms of the number of quantum beads. As N increases, the He-He PIMC pair correlation function shows a clear tendency to coincide with the experimental boson-liquid helium one at that temperature. It supports the picture of a helium droplet which carries the molecular impurity on its surface, as found earlier for other triplet dimers. © 2011 American Chemical Society.
Thu, 18 Oct 2012 07:31:29 GMThttp://hdl.handle.net/10261/582992012-10-18T07:31:29Z