Efficient, direct calculation of reaction rate coefficients based on a partially rearranged rovibrational Hamiltonian. A full-dimensional case study of the H + D HD + H reaction
arXiv:2607.11418 · doi:10.1021/acs.jpca.6c01349
The authors introduce a partially rearranged rovibrational Hamiltonian that enables efficient, fully quantum mechanical calculation of thermal reaction rate coefficients, and they apply it to compute rates for the H₂ + D → HD + H exchange reaction using a full‑dimensional potential energy surface.
Abstract
It is shown that an efficient, direct, and fully quantum mechanical calculation of thermal reaction rate coefficients requires a new, partially rearranged form of the numerically-constructed exact kinetic energy part of the rovibrational Hamiltonian expressed in internal coordinates. Using this Hamiltonian and an accurate, full-dimensional potential energy surface characterizing the H + H exchange reaction, developed by Mielke, Garrett, and Peterson (J. Chem. Phys. 2002, 116, 4142), reaction rate coefficients in the temperature range of K have been computed for the H + D HD + H reaction. The paper puts particular emphasis on the exact treatment of overall molecular rotation and on nuclear spin symmetry.