Recent Advances and Perspectives on Nonadiabatic Mixed Quantum–Classical Dynamics

Abstract

Nonadiabatic mixed quantum-classical (NA-MQC) dynamics methods form a class of computational theoretical approaches in quantum chemistry tailored to investigate the time evolution of nonadiabatic phenomena in molecules and supramolecular assemblies. NA-MQC is characterized by a partition of the molecular system into two subsystems: one to be treated quantum mechanically (usually but not restricted to electrons) and another to be dealt with classically (nuclei). The two subsystems are connected through nonadiabatic couplings terms to enforce self-consistency. A local approximation underlies the classical subsystem, implying that direct dynamics can be simulated, without needing precomputed potential energy surfaces. The NA-MQC split allows reducing computational costs, enabling the treatment of realistic molecular systems in diverse fields. Starting from the three most well-established methods-mean-field Ehrenfest, trajectory surface hopping, and multiple spawning-this review focuses on the NA-MQC dynamics methods and programs developed in the last 10 years. It stresses the relations between approaches and their domains of application. The electronic structure methods most commonly used together with NA-MQC dynamics are reviewed as well. The accuracy and precision of NA-MQC simulations are critically discussed, and general guidelines to choose an adequate method for each application are delivered.

WavePacket: A Matlab package for numerical quantum dynamics. III. Quantum‐classical simulations and surface hopping trajectories

“…This includes the main classes ket and rho for the implementation of quantum state vectors and density matrices in eigen representation, see Part II. Future releases of WavePacket will also include some of the more recent developments in SHT techniques, above all the various decoherence corrections in FSSH, to keep up with the recent progress in surface hopping . Moreover, also class definitions for various semi‐classical approaches based on Gaussian packets in phase space shall be implemented.…”

“…Moreover, there has been considerable methodological progress in SHT simulations in recent years . On the one hand, these efforts aim at overcoming the known problems of the earlier SHT approaches.…”

Different flavors of nonadiabatic molecular dynamics

“…This section aims at offering some selected examples of the types of photophysical and photochemical processes described by these techniques. For a more extended list of applications, the reader can refer to References (for quantum dynamics), References (for traveling Gaussian techniques), or References (for mixed quantum/classical methods).…”

“…The interested reader can consult for example References for discussions on the importance of adequately selecting initial conditions for nonadiabatic dynamics.…”

A comprehensive, self‐contained derivation of the one‐body density matrices from single‐reference excited‐state calculation methods using the equation‐of‐motion formalism

“…Additionally, the linear response (LR) variant of the single‐reference coupled cluster (CC) theory for excited states can be used for producing matrices that can be compared to those from CIS, TDA, and ADC, and classified among the second type of methods investigated in this contribution. Indeed, as for ADC and TD‐DFRT (where “R” stands for “response”), in the LR‐CC framework an auxiliary many‐body wave function (AMBW) has also been proposed for the assignment of excited states ansätze . For ADC, this has been done in addition to the ansatz already introduced in the intermediate states basis.…”