Ab initio study of low-lying electronic states of SnCl2+

Complete active space self-consistent field (CASSCF), multireference configuration interaction (MRCI), and restricted-spin coupled-cluster singles-doubles with perturbative triples [RCCSD(T)] calculations have been carried out on low-lying doublet and quartet states of SnCl2+, employing basis sets of up to aug-cc-pV5Z quality. Effects of core correlation and off-diagonal spin-orbit interaction on computed vertical ionization energies were investigated. The best theoretical estimate of the adiabatic ionization energy (including zero-point vibrational energy correction) to the 2A1 state of SnCl2+ is 10.093 ± 0.010 eV. The first photoelectron band of SnCl2 has also been simulated by employing RCCSD(T)/ aug-cc-pV5Z potential energy functions and including Duschinsky rotation and anharmonicity