Communication: GAIMS—Generalized <i>Ab Initio</i> Multiple Spawning for both internal conversion and intersystem crossing processes

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.

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“…As discussed in Ref. 176 , the problems to control the SOC phase, which severely affect TSH, does not occur in GAIMS. 39…”

Section: Intersystem Crossingmentioning

confidence: 99%

Recent Advances and Perspectives on Nonadiabatic Mixed Quantum–Classical Dynamics

2018

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“…Further developments 12 of GPU-SA-CASSCF/AIMS will include solvent and relativistic (intersystem crossing) effects to improve the comparison between theory and experiment. [70][71][72] …”

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confidence: 99%

GPU-Accelerated State-Averaged Complete Active Space Self-Consistent Field Interfaced with Ab Initio Multiple Spawning Unravels the Photodynamics of Provitamin D₃

Snyder

Curchod

Martı́nez

2016

J. Phys. Chem. Lett.

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Excited-state molecular dynamics is essential to the study of photochemical reactions, which occur under nonequilibrium conditions. However, the computational cost of such simulations has often dictated compromises between accuracy and efficiency. The need for an accurate description of both the molecular electronic structure and nuclear dynamics has historically stymied the simulation of medium- to large-size molecular systems. Here, we show how to alleviate this problem by combining ab initio multiple spawning (AIMS) for the nuclear dynamics and GPU-accelerated state-averaged complete active space self-consistent field (SA-CASSCF) for the electronic structure. We demonstrate the new approach by first-principles SA-CASSCF/AIMS nonadiabatic dynamics simulation of photoinduced electrocyclic ring-opening in the 51-atom provitamin D3 molecule.

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“…It is possible, in principle, to simulate the whole reaction cycle, for example, excitation of the system to the S 1 state, energy transfer via ISC or triplet sensitization, formation of a biradical on the triplet state, ISC back to the S 0 ground state and finally the relaxation dynamics on the ground state. While the techniques for all these steps are available, many of the above processes are too slow to be treated at fully ab initio level. We have therefore adopted a more pragmatic approach; we performed adiabatic ab initio molecular dynamics on the triplet state.…”

Section: Methodsmentioning

confidence: 99%

Molecular dynamics and metadynamics simulations of [2 + 2] photocycloaddition

Muchová

Bezek

Suchan

et al. 2017

Int J of Quantum Chemistry

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Triplet state mechanism of [2 + 2] photocycloaddition forming a cyclobutane ring from two ethylenes is investigated in the context of photocatalysis. High‐level ab initio calculations are combined with ab initio adiabatic molecular dynamics and ab initio metadynamics for rare events modeling. In a photocatalytic scheme, a reactant reaches the triplet state either via intersystem crossing (ISC) or triplet sensitization. The model system adopts a biradical structure, which represents energy intersection with the ground state. The system either completes cyclization or undergoes fragmentation into two olefinic units. The potential and free energy surfaces of the cyclobutane/ethylenes system are mapped with multireference approaches describing possible reaction pathways. To obtain a full picture of a double bond photoreactivity, ab initio adiabatic dynamical calculations were used to estimate reaction yields and to model the effects of excess energy. The potential use of density functional theory based approaches for [2 + 2] photocycloaddition was investigated for future simulations and design of realistic photocatalytic systems. Dynamical aspects of [2 + 2] photocycloaddition via a triplet state manifold are investigated by combining ab initio multireference methods and ab initio molecular dynamics and metadynamics. The reaction pathways are studied for a model system of two ethylenes forming a cyclobutane ring to provide a basis for further studies on design of photocatalytic systems.

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Communication: GAIMS—Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes

Cited by 102 publications

References 45 publications

Recent Advances and Perspectives on Nonadiabatic Mixed Quantum–Classical Dynamics

Recent Advances and Perspectives on Nonadiabatic Mixed Quantum–Classical Dynamics

GPU-Accelerated State-Averaged Complete Active Space Self-Consistent Field Interfaced with Ab Initio Multiple Spawning Unravels the Photodynamics of Provitamin D₃

Molecular dynamics and metadynamics simulations of [2 + 2] photocycloaddition

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Communication: GAIMS—Generalized Ab Initio Multiple Spawning for both internal conversion and intersystem crossing processes

Cited by 102 publications

References 45 publications

Recent Advances and Perspectives on Nonadiabatic Mixed Quantum–Classical Dynamics

Recent Advances and Perspectives on Nonadiabatic Mixed Quantum–Classical Dynamics

GPU-Accelerated State-Averaged Complete Active Space Self-Consistent Field Interfaced with Ab Initio Multiple Spawning Unravels the Photodynamics of Provitamin D3

Molecular dynamics and metadynamics simulations of [2 + 2] photocycloaddition

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Product

Resources

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GPU-Accelerated State-Averaged Complete Active Space Self-Consistent Field Interfaced with Ab Initio Multiple Spawning Unravels the Photodynamics of Provitamin D₃