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http://hdl.handle.net/10261/14181
Wed, 01 Oct 2014 16:52:53 GMT
20141001T16:52:53Z
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http://hdl.handle.net/10261/14181

Real space renormalization group methods and quantum groups
http://hdl.handle.net/10261/102722
Title: Real space renormalization group methods and quantum groups
Authors: MartínDelgado, Miguel Ángel; Sierra, Germán
Abstract: We apply real space renormalization group (RG) methods to study two quantum group invariant Hamiltonians, that of the XXZ model and the Ising model in a transverse field (ITF) defined in an open chain with appropriate boundary terms. The quantum group symmetry is preserved under the RG transformation except for the appearance of a quantum group anomalous term which vanishes in the classical case. We obtain correctly the line of critical XXZ models. In the ITF model the RG flow coincides with the tensor product decomposition of cyclic irreducible representations of SUq(2) with q4 = 1. © 1996 The American Physical Society
Tue, 30 Sep 2014 11:51:35 GMT
http://hdl.handle.net/10261/102722
20140930T11:51:35Z

Quasiclassical dynamics of the I2Ne2 vibrational predissociation: A comparison with experiment
http://hdl.handle.net/10261/102721
Title: Quasiclassical dynamics of the I2Ne2 vibrational predissociation: A comparison with experiment
Authors: García Vela, Alberto; RubayoSoneira, Jesús; Delgado Barrio, Gerardo; Villarreal, Pablo
Abstract: The vibrational predissociation dynamics of the I2(B,v)Ne2 complex is investigated for several vibrational levels of I2, using a quasiclassical trajectory approach. The time evolution of the population of nascent I2 fragments is calculated. A model is proposed which reproduces the results of the classical trajectories, and allows to obtain the lifetimes associated with the dissociation of the two van der Waals (vdW) bonds. The classical lifetimes are higher in general than the experimental ones of Zewail and coworkers [J. Chem. Phys. 97, 8048 (1992)]. The classical method appears to overestimate mechanisms of energy redistribution between the modes, which slow down the dissociation of the cluster. However, the behavior of the lifetimes with the initial iodine vibrational excitation is in very good agreement with experiment. A sequential path of fragmentation of the two weak bonds via direct predissociation is found to dominate, producing I2(B,v2)+2Ne fragments. Although with smaller probability, alternative dissociation paths are observed involving statistical mechanisms of internal energy redistribution. In these paths, the energy initially transferred by the iodine heats the vdW modes without breaking the complex. Further energy transfer produces either simultaneous or sequential dissociation of the two weak bonds in a rather evaporative way, populating the v2 and v3 exit channels. © 1996 American Institute of Physics.
Tue, 30 Sep 2014 11:41:42 GMT
http://hdl.handle.net/10261/102721
20140930T11:41:42Z

Quantummechanical study of the I2Ne vibrational predissociation dynamics: A threedimensional timedependent selfconsistentfield approach
http://hdl.handle.net/10261/102720
Title: Quantummechanical study of the I2Ne vibrational predissociation dynamics: A threedimensional timedependent selfconsistentfield approach
Authors: García Vela, Alberto
Abstract: A threedimensional timedependent selfconsistentfield (TDSCF) approach is proposed to study the vibrational predissociation of the I2(B)Ne van der Waals (vdW) complex. Jacobian coordinates are used within the assumption of zerototal angular momentum. In the method the total wave function is factorized such that the bending mode of the system is explicitly separated, while the coupling between the remaining two degrees of freedom is treated exactly. The decay dynamics of several resonances corresponding to different initial vibrational states of I2 is investigated through longtime wave packet propagations. Calculated resonance lifetimes are compared to experimental data and found to be in quantitative agreement with them. The results show that predissociation of the complex is mainly governed by the coupling between the I2 and the vdW stretching vibrations, whereas the bending mode has a rather weak effect on the dynamics. The good quality of the TDSCF description of this longtime dynamical process is due to the adaptation of the decoupling approximations applied in the method to the physical situation of the system. The validity of the approach is discussed in the light of the results. © 1996 American Institute of Physics.
Tue, 30 Sep 2014 11:37:27 GMT
http://hdl.handle.net/10261/102720
20140930T11:37:27Z

Prequantizable Poisson manifolds and Jacobi structures
http://hdl.handle.net/10261/102712
Title: Prequantizable Poisson manifolds and Jacobi structures
Authors: Chinea, Domingo; Marrero, Juan Carlos; León, Manuel de
Abstract: We prove that the total space of a prequantization bundle of a prequantizable Poisson manifold admits a Jacobi structure and, conversely, a regular Jacobi manifold is the prequantization bundle of a Poisson manifold. Illustrative examples are presented. c 1996 IOP Publishing Ltd
Tue, 30 Sep 2014 11:14:59 GMT
http://hdl.handle.net/10261/102712
20140930T11:14:59Z

Photoionization cross section and asymmetry parameter of LiH: A mixed GTO/STOCOS L2 basis set calculation
http://hdl.handle.net/10261/102701
Title: Photoionization cross section and asymmetry parameter of LiH: A mixed GTO/STOCOS L2 basis set calculation
Authors: CarmonaNovillo, Estela; Moccia, Roberto; Spizzo, Pietro
Abstract: The outershell photoionization cross section and the asymmetry parameter are computed ab initio for LiH up to a photon energy of 50 eV. The calculations employ an L2 Kmatrix technique at the StaticExchange Approximation (SEA) and at the Random Phase Approximation (RPA) levels, using mixed GTO/STOCOS bases. The results shows a fairly good internal coherence and are in good agreement with those obtained previously with pure Polynomial Spherical GTO (PSGTO) bases. @ 1996 Elsevier Science B.V.
Tue, 30 Sep 2014 10:48:08 GMT
http://hdl.handle.net/10261/102701
20140930T10:48:08Z

Phase transitions in staggered spin ladders
http://hdl.handle.net/10261/102696
Title: Phase transitions in staggered spin ladders
Authors: MartínDelgado, Miguel Ángel; Shankar, R.; Sierra, Germán
Abstract: We map spin ladders with nl legs and couplings J' across all rungs and 7(1 ± γ) along the legs, staggered in both directions, to a sigma model. Setting its θ = (2m + 1)π (where it is known to be gapless), we locate the critical curves in the γ versus J'/J plane at each nl, and spin S. The phase diagram is rich and has some surprises: When two gapped chains are suitably coupled, the combination becomes gapless. With nl, γ, and J'/J to control, the prospects for experimentally observing any one of these equivalent transitions are enhanced. We interpret our results in the framework of the resonating valence bond description of ladders. © 1996 The American Physical Society
Tue, 30 Sep 2014 10:24:45 GMT
http://hdl.handle.net/10261/102696
20140930T10:24:45Z

Perturbative calculation of intermolecular interactions in orthogonalized or biorthogonal basis sets
http://hdl.handle.net/10261/102691
Title: Perturbative calculation of intermolecular interactions in orthogonalized or biorthogonal basis sets
Authors: Surján, Péter R.; Pérez del Valle, C.
Abstract: Two versions of a manybody perturbation theory for the computation of molecular interaction energies are investigated. The methods are based on the partitioning of the secondquantized form of the dimer Hamiltonian written either in the orthogonalized basis of the monomer MOs, or, alternatively, in the original nonorthogonal dimer basis set handling the overlap by the biorthogonal formalism. The zerothorder Hamiltonian H0 is the sum of effective monomer Fockians and the zerothorder wave functions are exact eigenfunctions of H0. Full antisymmetry is ensured by the secondquantized formalism. Basis set superposition error is accounted for by the counterpoise correction recipe. Results for He2, (H2)2 and (H2O)2 indicate the reliability of the biorthogonal technique. © SpringerVerlag 1996
Tue, 30 Sep 2014 10:06:04 GMT
http://hdl.handle.net/10261/102691
20140930T10:06:04Z

On the geometry of nonholonomic Lagrangian systems
http://hdl.handle.net/10261/102687
Title: On the geometry of nonholonomic Lagrangian systems
Authors: León, Manuel de; Martín de Diego, David
Abstract: We present a geometric framework for nonholonomic Lagrangian systems in terms of distributions on the configuration manifold. If the constrained system is regular, an almost product structure on the phase space of velocities is constructed such that the constrained dynamics is obtained by projecting the free dynamics. If the constrained system is singular, we develop a constraint algorithm which is very similar to that developed by Dirac and Bergmann, and later globalized by Gotay and Nester. Special attention to the case of constrained systems given by connections is paid. In particular, we extend the results of Koiller for Caplygin systems. An application to the socalled nonholonomic geometry is given. © 1996 American Institute of Physics.
Tue, 30 Sep 2014 09:52:20 GMT
http://hdl.handle.net/10261/102687
20140930T09:52:20Z

On frames defined by horizontal spaces
http://hdl.handle.net/10261/102684
Title: On frames defined by horizontal spaces
Authors: León, Manuel de; Ortaçgil, Ercüment
Tue, 30 Sep 2014 09:26:45 GMT
http://hdl.handle.net/10261/102684
20140930T09:26:45Z

Nonlinear gauge realization of spacetime symmetries including translations
http://hdl.handle.net/10261/102679
Title: Nonlinear gauge realization of spacetime symmetries including translations
Authors: Julve, Jaime; LópezPinto, A.; Tiemblo, Alfredo; Tresguerres, Romualdo
Abstract: We present a general scheme for the nonlinear gauge realizations of spacetime groups on coset spaces of the groups considered. In order to show the relevance of the method for the rigorous treatment of the translations in gravitational gauge theories, we apply it in particular to the affine group. This is an illustration of the family of spacetime symmetries having the form of a semidirect product H ⊗ T, where H is the stability subgroup and T are the translations. The translational component of the connection behaves like a true tensor under H when coset realizations are involved. c Plenum Publishing Corporation
Tue, 30 Sep 2014 09:17:36 GMT
http://hdl.handle.net/10261/102679
20140930T09:17:36Z