Accurate Fitting of Analytic Potential Energy Function for SiH Radical

The reasonable dissociation limit of the ground state(X2П)of SiH radical is attained by employing the molecular reaction dynamics theory.The accurate equilibrium geometry and harmonic frequency of this state are calculated using the coupled-cluster theory [QCISD(T)] and a very large basis set(cc-PVQZ).The potential energy curve is also calculated over the internuclear separation from 0.10 to 1.71 nm.The equilibrium separation,harmonic frequency and dissociation energy of the vertical excitation energies from the ground state to the A1Σ+,B1П and b3П states are calculated to be 0.152 37 nm,2 047.522 4 cm-1,respectively.The ab initio calculated points are fitted into analytic form using 4-,5-,6-and 7-parameter Murrell-Sorbie functions.It has been pointed out that only 6-parameter Murrell-Sorbie function can give the best results.