Computational Study of the Rare Gas Fluorohydrides, Cyanohydrides, and Isocyanohydrides: Structures, Reactions, and Electronic Spectra

Abstract

Little work on the electronic excited states of the family of HRgY (where Rg = rare gas and Y = electronegative group) compounds exist. There are two problems that are studied. The first is work aimed at extending the HRgY excited state area of research to include more work done on the electronic excited states of HRgF (where Rg = Ar, Kr, Xe, Rn) at the time-dependent density functional theory (TDDFT) level of theory. The effects of the Rg matrix and relativistic effects on the electronic spectra were investigated with scalar relativistic effects and spin-orbit coupling. The matrix caused the excitation energies to blue-shift (for all HRgF) and scalar relativistic effects caused them to red-shift (most significantly for HRnF). Spin-orbit coupling in HRnF altered its electronic spectrum significantly. A brief investigation of the computational efficiency of model core potentials (MCPs) in comparison to all-electron (AE) basis sets was done and it was found that MCP basis sets speed up excited state calculations while still giving similar results as the AE basis sets. The second problem addressed is the low-lying excited states (with spin-orbit coupling), structure, and reactions of HRnY and HXeY (where Y = CN, NC), specifically their isomerization and dissociation reactions. Isotopic substitution on reaction rates and the effectiveness of several pseudopotential basis sets was also studied for these systems. The work was done at the DFT, TDDFT, and Møller-Plesset (MP2) levels of theory.