Theoretical studies of [Si4NO]− clusters with ab initio MO and DFT methods

Various isomers of [Si4NO]− cluster have been studied at both UHF/6-31G∗ and UB3LYP/6-31G∗ levels. The optimized structures and harmonic vibrational frequencies were calculated at both levels of approximations. Two obviously different groups of isomers have been found as in the case of [Si4NO]+, and the Si4− cluster shows higher reactivity toward NO molecule than Si4+. The differences between anionic and cationic Si4NO clusters and the comparison with the experimental results were discussed.