Vibration spectrum calculations of isotopic species of hydrogen sulfide using the discrete variable representation (DVR) method

Abstract

In this work, a modified three-dimensional discrete variable representation (MDVR3D) program, which could be used to calculate the bound state vibration spectrum of some triatomic molecules is developed. The sine basis functions are chosen to define the DVR for the radial coordinates for this new program. Both the three-dimensional discrete variable representation (DVR3D) program and the MDVR3D program are used to calculate the vibration energy levels of the isotopic species of hydrogen sulfide (H232S, H233S, H234S, D232S, D233S, D234S, T232S, T233S, T234S). The calculated vibration energy levels from the MDVR3D program are consistent with the counterparts from the DVR3D program, which means that they are good procedures for calculating the bound state energy levels of the triatomic molecules and testing the quality of the potential energy surface (PES). The comparison of the experimental and theoretical vibration energy levels for the nine isotopic species of hydrogen sulfide molecule is made and shows good consistency. This work forms the basis for dealing with the rotational spectrum calculations and presents the first theoretical results for D233S, T232S, T233S, and T234S. Future spectrum observations are needed to compare with these new results.