An ab initio study on the ground state HBO–BOH system

Abstract

Ab initio electronic structure theory has been employed in order to investigate the ground state potential energy hypersurfaces of the HBO–BOH system. Geometries, dipole moments, harmonic vibrational frequencies, and infrared intensities of two equilibrium and two transition state [inversion (bending through linear geometry) and isomerization] structures were determined at the self-consistent-field (SCF), configuration interaction with single and double excitations (CISD), coupled cluster with single and double excitations (CCSD), and CCSD with perturbative triple excitations [CCSD(T)] levels of theory using three basis sets. The theoretically predicted geometries and physical properties agree very well with available experimental values. At the highest level of theory employed in this study, CCSD(T) using triple zeta plus double polarization with higher angular momentum function [TZ2P(f,d)] basis set, the linear HBO molecule is predicted to be 45.0 kcal/mol more stable relative to the bent BOH species; with the zero-point vibrational energy (ZPVE) correction this energy separation becomes 44.4 kcal/mol; the classical barrier height for the inversion motion of the bent BOH molecule is predicted to be 3.5 kcal/mol and the barrier height with the ZPVE correction is 3.0 kcal/mol; the classical activation energy for the isomerization (1,2 hydrogen shift) reaction BOH→HBO is determined to be 29.4 kcal/mol and the activation energy with the ZPVE correction is 26.6 kcal/mol.