AN ABINITIO STUDY OF THE STRUCTURE AND INFRARED-SPECTRUM OF SI3C

The ground state geometry and vibrational spectrum of the previously not studied silicon-carbon cluster Si3 C has been investigated. Several possible isomeric structures are studied at the Hartree-Fock level. The energetically most favorable isomer is found to be a rhomboidal C2-upsilon structure with two equivalent silicon atoms and a transannular Si-C bond. Harmonic frequencies, isotopic shifts, and infrared intensities are calculated using many-body perturbation theory to second order and found to be in excellent agreement with recent experimental results supporting the identification of a new tetra-atomic silicon-carbon cluster.