A thermofield-based multilayer multiconfigurational time-dependent Hartree approach to non-adiabatic quantum dynamics at finite temperature

We introduce a thermofield-based formulation of the multilayer multiconfigurational time-dependent Hartree (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 a 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. Furthermore, we find our results to agree well with existing studies on the pyrazine model based on the pMCTDH method. Published under an exclusive license by AIP Publishing

Automated summary

This study introduces a thermofield-based formulation of the multilayer multiconfigurational time-dependent Hartree (MCTDH) method to investigate finite temperature effects on non-adiabatic quantum dynamics. By transferring bosonic many-body MCTDH to the finite temperature framework of thermal quasi-particle TFD, temperature effects on ultrafast internal conversion dynamics in pyrazine can be efficiently accounted for. The results are found to agree well with existing studies on the pyrazine model based on the pMCTDH method.