Implementation of quantum-classical mapping approaches for nonadiabatic molecular dynamics in the PySurf package

ChemRxiv

Abstract

Quantum-classical methods for nonadiabatic molecular dynamics, based on the Mayer-Miller-Stock-Thoss mapping, are implemented in the open source computer package PySurf. This complements the implementation of surface hopping approaches performed in previous works, and leads to a unified code that allows nonadiabatic dynamics simulations using various mapping approaches (Ehrenfest dynamics, the linearized semiclassical initial value representation, the Poisson-bracket mapping equation, the “unity” approach for the indentity operator, and the spin mapping method) as well as different flavours of surface hopping (fewest-switches, Landau-Zener, and a mapping-inspired scheme). Furthermore, a plugin is developed to provide diabatic vibronic models in a sum-of-products form. This opens the way to the benchmark of different types of quantum-classical propagators on different models, against exact quantum dynamical simulations performed, e.g., by the multiconfigurational time- dependent Hartree method. Illustrative calculations, performed using the whole set of available propagators, are presented for different harmonic and anharmonic two-state models, exhibiting various degrees of correlation between vibrational modes.

Authors 5

1. David Picconi

   Heinrich Heine University Düsseldorf

   Affiliation as printed

   Heinrich Heine University Düsseldorf

2. Maximilian F. S. J. Menger

   Heidelberg University

   Affiliation as printed

   Heidelberg University

3. Elisa Palacino‐González

   Heinrich Heine University Düsseldorf

   Affiliation as printed

   Heinrich Heine University Düsseldorf

4. Edison X. Salazar Aachen

   Leiden University

   Affiliation as printed

   Leiden University

5. Shirin Faraji

   Heinrich Heine University Düsseldorf

   Affiliation as printed

   Heinrich Heine University Düsseldorf