ASSIGNMENT OF THE VIBRATIONAL-SPECTRA OF POLYSILANE AND ITS OLIGOMERS

The dynamical properties of polysilane (also, polysilylene) have been studied by the scaled quantum mechanical oligomer force field (SQMOFF) approach. The analysis of the vibrational spectrum of polysilane is based on the assignments of the available vibrational spectra of small polysilane oligomers, Si2H6, Si3H8, and Si4H10, on the basis of the scaled ab initio force fields at the 6-31G basis set level. The phonon dispersion curves of all-trans-and gauche-polysilanes have been obtained. The calculated vibrational spectrum of polysilane indicates that polysilane is most likely in a disordered form, where trans and gauche segments are randomly distributed. The experimental Raman spectrum of polysilane has been assigned on the basis of the present calculations.