ISOMERISM AND SPIN-VIBRONIC ENERGY-LEVELS OF SILICON NITROXIDE

The ground-state potential-energy surface of silicon nitroxide has bee n investigated theoretically by the internally contracted multi refere nce configuration interaction (MRCI) method from complete active space self consistent held (CASSCF) reference wavefunctions using large orb ital expansions. Three different linear isomers have been identified o n the ground electronic state potential-energy surface, corresponding to the chemical structures SiNO, NSiO and SiON. Their geometries and r elative energies have been estimated. Variational theory has been used to calculate the vibronic levels for values of the total angular mome ntum J=1/2, 3/2, including dynamic non-adiabatic interactions between electronic spin, orbital and vibrational angular momenta. The predicte d vibronic frequencies are expected to be accurate for all three isome rs.