Total Angular Momentum Conservation in Ehrenfest Dynamics with a Truncated Basis of Adiabatic States

2023/11/28 by Zhen Tao, Tao, Zhen, Xuezhi Bian +9 · 2 citations
Engineering · Physics and Astronomy · #Advanced Chemical Physics Studies #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Molecular Junctions and Nanostructures #Spectroscopy and Quantum Chemical Studies

paper · pdf · doi:10.48550/arxiv.2311.16995

openalex publication_date 2023/11/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We show that standard Ehrenfest dynamics does not conserve linear and angular momentum when using a basis of truncated adiabatic states. However, we also show that previously proposed effective Ehrenfest equations of motion[Amano2005,Krishna2007] involving the non-Abelian Berry force do maintain momentum conservation. As a numerical example, we investigate the Kramers' doublet of the methoxy radical using generalized Hartree-Fock with spin-orbit coupling and confirm angular momentum is conserved with the proper equations of motion. Our work makes clear some of the limitations of the Born-Oppenheimer approximation when using ab initio electronic structure theory to treat systems with unpaired electronic spin degrees of freedom and we demonstrate that Ehrenfest dynamics can offer much improved, qualitatively correct results.

Cited by

• The Phase-Space Way To Electronic Structure Theory and Subsequently Chemical Dynamics
• Conical Intersections and Electronic Momentum As Viewed From Phase Space Electronic Structure Theory

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