A Thermofield-based Multilayer Multiconfigurational Time-Dependent Hartree Approach to Non-Adiabatic Quantum Dynamics at Finite Temperature

TL;DR

This paper presents a novel thermofield-based multilayer MCTDH method to accurately simulate finite temperature effects on non-adiabatic quantum dynamics, demonstrated through pyrazine's ultrafast internal conversion.

Contribution

It introduces a thermofield formulation of ML-MCTDH for finite temperature quantum dynamics, bridging bosonic many-body theory with thermal quasi-particle TFD.

Findings

Finite temperature effects are efficiently incorporated into multilayer thermofield states.

Results agree well with existing $ ho$MCTDH studies on pyrazine.

The method accurately captures ultrafast internal conversion dynamics.

Abstract

We introduce a thermofield-based formulation of the multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) method to study finite temperature effects on non-adiabatic quantum dynamics from a non-stochastic, wave-function perspective. Our approach is based on the formal equivalence of bosonic many-body theory at zero temperature with doubled number of degrees of freedom and the thermal quasi-particle representation of bosonic thermofield dynamics (TFD). This equivalence allows for a transfer of bosonic many-body MCTDH as introduced by Wang and Thoss to the finite temperature framework of thermal quasi-particle TFD. As an application, we study temperature effects on the ultrafast internal conversion dynamics in pyrazine. We show, that finite temperature effects can be efficiently accounted for in the construction of multilayer expansions of thermofield states in the framework presented herein. Further, we find our results to agree well with existing studies on the pyrazine model based on the $\rho$MCTDH method.