An ab initio study of the structure, torsional potential energy function, and electric properties of disilane, ethane, and their deuterated isotopomers

Highly accurate ab initio computations of the molecular structure and properties, torsional potential energy function, and harmonic force field of disilane and ethane have been carried out. Equilibrium parameters as well as vibrational corrections have been evaluated. In addition, for these systems a vibrational averaging procedure has been employed for calculating the dipole moment of molecules which have no permanent dipole moment, i.e., SiH(3)SiD(3) and CH(3)CD(3). The molecular and spectroscopic properties calculated for ethane and its isotopomers provide a calibration against known experimental data, allowing us to estimate the reliability of our computed results for disilane for which there is much less experimental data. The goal of the present study is to predict the molecular parameters, with estimated uncertainties, that determine the microwave spectrum of SiH(3)SiD(3).