On the identity of the identity operator in nonadiabatic linearized semiclassical dynamics

• Published in: The Journal of chemical physics Vol. 150; no. 7; p. 071101
• Main Authors: Saller, Maximilian A C, Kelly, Aaron, Richardson, Jeremy O
• Format: Journal Article
• Language: English
• Published: United States 21.02.2019
• ISSN: 1089-7690
• DOI: 10.1063/1.5082596

Simulating the nonadiabatic dynamics of condensed-phase systems continues to pose a significant challenge for quantum dynamics methods. Approaches based on sampling classical trajectories within the mapping formalism, such as the linearized semiclassical initial value representation (LSC-IVR), can be used to approximate quantum correlation functions in dissipative environments. Such semiclassical methods however commonly fail in quantitatively predicting the electronic-state populations in the long-time limit. Here we present a suggestion to minimize this difficulty by splitting the problem into two parts, one of which involves the identity and treating this operator by quantum-mechanical principles rather than with classical approximations. This strategy is applied to numerical simulations of spin-boson model systems, showing its potential to drastically improve the performance of LSC-IVR and related methods with no change in the equations of motion or the algorithm in general, but rather by simply using different functional forms of the observables.