Isomerism and spin–vibronic energy levels of silicon nitroxide

Abstract

The ground-state potential-energy surface of silicon nitroxide has been investigated theoretically by the internally contracted multi reference configuration interaction (MRCI) method from complete active space self consistent field (CASSCF) reference wavefunctions using large orbital expansions. Three different linear isomers have been identified on the ground electronic state potential-energy surface, corresponding to the chemical structures SiNO, NSiO and SiON. Their geometries and relative energies have been estimated. Variational theory has been used to calculate the vibronic levels for values of the total angular momentum quantum number J=½, , including dynamic non-adiabatic interactions between electronic spin, orbital and vibrational angular momenta. The predicted vibronic frequencies are expected to be accurate for all three isomers.