MCTDH ROVIBRATIONAL STATES AND STATE-TO-STATE INELASTIC SCATTERING CALCULATIONS ON THE H2O-H2 SYSTEM

Water, an essential ingredient of life, is prevalent in space and various media. H$_2$O in the gas phase is the major polyatomic species in the interstellar medium (ISM) and a primary target of current studies of collisional dynamics. In recent years a number of theoretical and experimental studies have been devoted to H$_2$O-X (with X=He, H$_2$, D$_2$, Ar, …) elastic and inelastic collisions in an effort to understand rotational distributions of H$_2$O in molecular clouds. In this work we are following those studies and will present benchmark calculations of rovibrational states and resonances of the H$_2$O-H$_2$ cluster in the rigid rotor approximation using the MultiConfiguration Time Dependent Hartree (MCTDH) approach. We will also present the first state-to-state inelastic scattering results of the H$_2$O+H$_2$ process in the rigid rotor approximation using the MCTDH approach. These calculations will serve as a foundation for similar triatomic – linear molecule interactions which are usually computationally expensive using standard calculations methods