ABINITIO STUDY OF LOW-LYING ELECTRONIC STATES OF THE SINN RADICAL

The equilibrium geometries, excitation energies, force constants and vibrational frequencies for the low-lying electronic states X 3-SIGMA-, a 1-DELTA, A 3-PI and 1 1-PI of the SiNN radical have been calculated at the MRSDCI level with a double-zeta plus polarization basis set. Our calculations imply that SiNN is a bonding and not a van der Waals molecule. Our calculated excitation energy for X 3-SIGMA- --> A 3-PI and vibrational frequencies for these two states are in good agreement with experiment. Electronic transition dipole moment, oscillator strength for the A 3-PI --> X 3-SIGMA- transition, radiative lifetime for the A 3-PI state and the spin properties for the X 3-SIGMA- state are calculated based on the MRSDCI wavefunctions, predicting results in reasonable agreement with available experimental data.