Energetic and radiative properties of the A-=SUP=-2-=/SUP=-Sigma-=SUP=-+-=/SUP=--X-=SUP=-2-=/SUP=- system of the OH radical: ab initio calculation and non-adiabatic simulation

Abstract

A quantum-chemical model for non-adiabatic simulation of the energetic and radiative properties of the A2Sigma+-X2 system of the OH radical is presented. The electronic structure parameters (potential energy functions and electronic matrix elements of the spin-orbit and the electron-rotation interactions) are obtained by means of ab initio calculation. The reliability of the performed calculations is confirmed by comparing ab initio estimates with experimental values for the spin-orbit splitting, the -doubling parameters of the X2 state, and the γ-doubling of the A2Sigma+ state. The frequencies and Einstein coefficients for rovibronic transitions between the A2Sigma+ and X2 states are simulated in a wide range of rovibrational excitations. The obtained values are in quantitative agreement with the data available from literature. Keywords: OH radical, ab initio calculation, non-adiabatic interaction, fine structure, radiative transition probability.