Overcoming positivity violations for density matrices in surface hopping

Abstract

Fewest-switches surface hopping (FSSH) has emerged as one of the leading methods for modeling the quantum dynamics of molecular systems. While its original formulation was limited to adiabatic populations, the growing interest in the application of FSSH to coherent phenomena prompts the question how one should construct a complete density matrix based on FSSH trajectories. A straightforward solution is to define adiabatic coherences based on wavefunction coefficients. In this Paper, we demonstrate that inconsistencies introduced in the density matrix through such treatment may lead to a violation of positivity. We furthermore show that a recently proposed coherent generalization of FSSH results in density matrices that satisfy positivity, while yielding an improved accuracy throughout much (but not all) of parameter space.

References in corpus (4)

• Benchmarking Semiclassical and Perturbative Methods for Real-time Simulations of Cavity-Bound Emission and Interference
• Electron spin relaxation in radical pairs: Beyond the Redfield approximation
• A Reciprocal-Space Formulation of Surface Hopping
• A Reciprocal-Space Formulation of Mixed Quantum-Classical Dynamics

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• Heisenberg dynamics of mixed quantum-classical systems