THE VIBRATIONAL FREQUENCIES OF HALOSIL YLENES HSiX (X = F, Cl, Br)

Abstract

Author Institution: Department of Chemistry, The University of KentuckyThere are a number of ambiguities and curiosities found in the published Si-H stretching vibrational frequencies of the ground states, $\tilde{X}^{1}A^{\prime}$, and first excited singlet states, $\tilde{A}^{1}A$, of the halosilylenes HSiF, HSiCl, and HSiBr. Here we have investigated these molecules using self-consistent field. SCF, configuration interaction including all single and double excitations, CISD, and triple excitations, CISDT, and complete active space, CAS-SCF, quantum mechanical methods. For the ground and first excited triplet states, all these methods give similar results, but for the excited singlet states, only the CASSCF results are believable