New ab initio potential energy surfaces for both the ground (X̃1A') and excited (Ã1A″) electronic states of HSiCl and the absorption and emission spectra of HSiCl/DSiCl.

New ab initio potential energy surfaces for the ground (X̃1A') and excited (Ã1A″) electronic states of HSiCl were obtained by using the single and double excitation coupled-cluster theory with a noniterative perturbation treatment of triple excitations and the multi-reference configuration interaction with Davidson correction, respectively, employing an augmented correlation-consistent polarized valence quadruple zeta basis set. For the excited state Ã1A″, an extended active space (18 electrons in 12 orbitals) was used. The calculated vibrational energy levels of HSiCl and DSiCl of the ground and excited electronic states are in better agreement with the available experimental values than the previous theoretical results. In addition, with the calculated transition dipole moment, the absorption and emission spectra of HSiCl and DSiCl were calculated using an efficient single Lanczos propagation method and are in reasonable agreement with the available observed spectra.