Energy-Conserving Coupled Trajectory Mixed Quantum Classical Dynamics

TL;DR

This paper introduces CTMQC-E, an energy-conserving modification of the coupled-trajectory mixed quantum classical dynamics method, improving accuracy in simulating photo-chemical processes by ensuring energy conservation.

Contribution

The paper presents a new algorithm, CTMQC-E, that modifies the force calculation in CTMQC to guarantee energy conservation during simulations.

Findings

CTMQC-E accurately predicts scattering in Tully's model.

CTMQC-E successfully models photoisomerization in retinal.

Energy conservation is restored in the modified method.

Abstract

The coupled-trajectory mixed quantum classical method (CTMQC), derived from the exact factorization approach, has successfully predicted photo-chemical dynamics in a number of interesting molecules, capturing population transfer and decoherence from first-principles. However, due to the approximations made, CTMQC does not guarantee energy conservation. We propose a modified algorithm, CTMQC-E, which redefines the integrated force in the coupled-trajectory term so to restore energy conservation, and demonstrate its accuracy on scattering in Tully's extended coupling region model and photoisomerization in a retinal chromophore model.