The Analytical Potential Energy Function for the Ground-state SiH Molecule

The molecular reaction dynamics theory and group theory are employed to attain the reasonable dissociation limit of the X2 ∏ state of SiH molecule.The equilibrium separations,the harmonic frequencies and the dissociation energies about the X2 ∏ state have been calculated through Gaussian 03 program packet by the methods of QCISD(T),QCISD,B3LYP with the basis sets 6-311G(df,pd),6-311G(df,2pd),6-311G(2df,pd)and 6-311G(2df,2pd).By the comparison of the attained results with the experiments,it is concluded that the QCISD(T)/6-311G(df,2pd)is the most suitable for the ground state energy calculation of the X2 ∏ state SiH molecule.At the QCISD(T)/6-311G(df,2pd)theory level the whole potential energy curve for this state is further scanned,then has a least squares fitted to the analytic Murrell-Sorbie function form.Finally the spectroscopy constants and force constants are calculated,which are in good agreement with the experimental data.