Electronic and spin-rovibrational spectroscopy of the HPS+ cation

Abstract

Using post Hartree-Fock multi-configuration interaction ab initio approaches, the six (four) doublet (quartet) lowest electronic states of thioxophosphane cation, HPS+, are treated. These electronic states are mapped along the internal coordinates, including the HP, PS distances and in-plane HPS bending angle. Several potential minima are located where long-lived HPS+ ions can be found. Also, computations show that the (X˜2A', 12A", 22A", 22A', 14A' and 14A") states are bound, for which we generate their 3D-potential energy surfaces (3D-PESs). After nuclear motion treatments, we determine the rotational and vibrational constants of these states and the pattern of their rovibrational levels up to 4000 cm−1 above the corresponding vibrational ground state level. For instance, the RCCSD(T)/aug-cc-pV(5 + d)Z anharmonic frequencies of HPS+(X˜2A') are computed ν1 = 2237.7, ν2 = 543.0, ν3 = 686.8 (in cm−1). For the lowest electronic excited state (HPS+(12A")), these frequencies change to ν1 = 2330.5, ν2 = 254.6 and ν3 = 749.6 (in cm−1). Several anharmonic resonances are identified. Besides, a very accurate adiabatic ionization energy of HPS (= 9.3173 eV) is deduced using the (U)CCSDT(Q)/aug-cc-pV(T + d)Z approach and where the core-valence (ΔCV), scalar relativistic (ΔSR) and zero point vibrational energy (ΔZPE) corrections are included. Our spectroscopic data should be useful for identifying this ion in laboratory and in media where reactive collisions between PS/PS+ + H+/H or HP/HP+ + S+/S are taking place.