Computational analysis of vibrational frequencies and rovibrational spectroscopic constants of hydrogen sulfide dimer using MP2 and CCSD(T).

Previous studies have shown that the weakly bonded H2S dimer demands high level quantum chemical calculations to reproduce experimental values. We investigated the hydrogen bonding of H2S dimer using MP2 and CCSD(T) levels of theory in combination with aug-cc-pV(D,T,Q)Z basis sets. More precisely, the binding energies, potential energy curves, rovibrational spectroscopic constants, decomposition lifetime, and normal vibrational frequencies were calculated. In addition, we introduced the local mode analysis of Konkoli-Cremer to quantify the hydrogen bonding in the H2S dimer as well as providing for the first time the comprehensive decomposition of normal vibrational modes into local modes contributions, and a decomposition lifetime based on rate constant. The local mode force constant of the H2S dimer hydrogen bond is smaller than that of the water dimer, in accordance with the weaker hydrogen bonding in the H2S dimer.