Coordinate systems and kinetic energy operators for multi-configurational time-dependent Hartree calculations studying reactions of methane

摘要

Accurate full-dimensional quantum state-resolved calculations studying reactions of methane currently rely on the multi-configurational time-dependent Hartree (MCTDH) approach and curvilinear coordinate systems. The coordinate systems used in MCTDH simulations of the reactive scattering of methane were based on a coordinate system and kinetic energy operator introduced by Evenhuis et al.(2007).In this coordinate system, the body-fixed frame is tied to the methyl fragment. Here it is shown that a revised definition of the methyl-fixed frame can reduce the correlation between the rotation of the methyl fragment and its internal motion. Furthermore, a new coordinate system which defines the body-fixed frame using the Jacobi vector associated with the dissociating bond and the symmetry axis of the methyl fragment is introduced. This coordinate system is designed for MCTDH simulations of the dissociative chemisorption of methane on surfaces. (c)2018 Elsevier B.V. All rights reserved.