SPECTROSCOPIC CHARACTERIZATION OF THE UNSATURATED HYDROCABONS C3H AND C5H USING HIGHLY CORRELATED AB INITIO METHODS

Abstract

Unsaturated carbon chains and hydrocarbons can play important roles in the chemical evolution of the interstellar sources. They can be considered as building blocks of large carbon species. Charged chains are reactive species that can participate in many chemical processes at low temperatures. We present state-of-the art ab initio calculations focused to the determination of equilibrium structures and spectroscopic parameters corresponding to various electronic states of the C3H and C5H chains containing an odd number of carbon atoms. Both species C3H and C5H present various isomers that can be linear or cyclic forms. All of them show non-zero dipole moments that can help their identification. Some of them are relatively stable structures. Because, astronomers have dedicated special attention to the charged species during the last years, calculations of cations and anions are also provided. For all the cases, neutral, negative and positive charged species, excitations to the low electronic states are determined. We provide electron affinities and ionization potentials. Spin-orbit effects are predicted. The employed methodology was first used to describe other carbon chains containing even number of atoms