Multi-configurational Ehrenfest simulations of ultrafast nonadiabatic dynamics in a charge-transfer complex

Abstract

Analysis of trajectory similarity and configuration similarity in on-the-fly surface-hopping simulation on multi-channel nonadiabatic photoisomerization dynamics

Multi-layer Gaussian-based multi-configuration time-dependent Hartree (ML-GMCTDH) simulations of ultrafast charge separation in a donor–acceptor complex

“…Long-lived coherent vibronic features as observed in the present model complex indeed appear in spatially extended systems with dense electronic manifolds, too. 40,51,65 As underscored by our previous studies, 11,52 more approximate quantum-classical approaches may fail for this type of systems. For these reasons, on-the-fly dynamics for these systems, which is often restricted to Ehrenfest molecular dynamics 66 or Surface-Hopping dynamics, 67 remain highly challenging.…”

“…These methods have a long tradition in semiclassical dynamics and include classically evolving Gaussian wavepackets (GWPs), 1,2 notably Heller's Thawed Gaussians (TGs) 3 and Frozen Gaussians (FGs), 4 variationally evolving GWPs, 5 and variational GWP superpositions. 6,7 Over recent years, many methods have been developed that are built on these basic concepts, e.g., the Full Multiple Spawning (FMS) approach, 8 the Coupled Coherent States method, 9 the multiconfigurational Ehrenfest approach, 10,11 and the variational Multi-Configurational Gaussian (vMCG) method. 12,13 An important area of application is on-the-fly dynamics, e.g., in the Ab Initio Multiple Spawning (AIMS) approach, 14,15 the Direct Dynamics variational Multi-Configurational Gaussian (DD-vMCG) method, [16][17][18] the ab initio Multiple Cloning Multi-Configurational Ehrenfest (AIMC-MCE) approach, 19 and the on-the-fly ab initio (OTF-AI) semiclassical dynamics method.…”

“…12,13 An important area of application is on-the-fly dynamics, e.g., in the Ab Initio Multiple Spawning (AIMS) approach, 14,15 the Direct Dynamics variational Multi-Configurational Gaussian (DD-vMCG) method, [16][17][18] the ab initio Multiple Cloning Multi-Configurational Ehrenfest (AIMC-MCE) approach, 19 and the on-the-fly ab initio (OTF-AI) semiclassical dynamics method. 20 Also, statistical treatments, 21 system-bath problems, 22 and quantum-classical hybrid approaches 11,23 are naturally amenable to a GWP based treatment.…”

“…More approximate methods like Ehrenfest dynamics fail entirely for this system, 11 while Multi-Configuration Ehrenfest (MCE) approaches lead to slow convergence for a limited number of modes (typically for 10-40 modes). 11,52 For similar numbers of modes, vMCG dynamics are difficult to converge, too, while the G-MCTDH approach works well, but becomes rapidly expensive. 52 Using 2L-GMCTDH, converged calculations could be performed up to 100 modes.…”

Quantum system-bath dynamics with quantum superposition sampling and coupled generalized coherent states

“…The idea of randomness has also been used in recent MCEv2 calculations carried out by the group of Burghardt. 27 Here, we will look at random sampling of the quantum subsystem more systematically. An important consideration is that using this sampling technique does not add any significant computational cost…”