QM/MM Nonadiabatic Dynamics: the SHARC/COBRAMM Approach

2021 ◽  
Author(s):  
Davide Avagliano ◽  
Matteo Bonfanti ◽  
Marco Garavelli ◽  
Leticia González
Keyword(s):  
Nonadiabatic Dynamics

Analysis of the Bath Motion in the MM-SQC Dynamics Using Unsupervised Machine Learning Dimensionality Reduction Approaches: Principal Component Analysis

2020 ◽  
Author(s):  
Jiawei Peng ◽  
Yu Xie ◽  
Deping Hu ◽  
Zhenggang Lan
Keyword(s):  
Machine Learning ◽  
Principal Component Analysis ◽  
Collective Motion ◽  
Principal Component ◽  
Component Analysis ◽  
Nonadiabatic Dynamics ◽  
Trajectory Data ◽  
Unsupervised Machine Learning ◽  
Physical Knowledge ◽  
Vibronic Couplings

The system-plus-bath model is an important tool to understand nonadiabatic dynamics for large molecular systems. The understanding of the collective motion of a huge number of bath modes is essential to reveal their key roles in the overall dynamics. We apply the principal component analysis (PCA) to investigate the bath motion based on the massive data generated from the MM-SQC (symmetrical quasi-classical dynamics method based on the Meyer-Miller mapping Hamiltonian) nonadiabatic dynamics of the excited-state energy transfer dynamics of Frenkel-exciton model. The PCA method clearly clarifies that two types of bath modes, which either display the strong vibronic couplings or have the frequencies close to electronic transition, are very important to the nonadiabatic dynamics. These observations are fully consistent with the physical insights. This conclusion is obtained purely based on the PCA understanding of the trajectory data, without the large involvement of pre-defined physical knowledge. The results show that the PCA approach, one of the simplest unsupervised machine learning methods, is very powerful to analyze the complicated nonadiabatic dynamics in condensed phase involving many degrees of freedom.

High-Fidelity First Principles Nonadiabaticity: Diabatization, Analytic Representation of Global Diabatic Potential Energy Matrices, and Quantum Dynamics

2021 ◽  
Author(s):  
Yafu Guan ◽  
Changjian Xie ◽  
David R. Yarkony ◽  
Hua Guo
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
First Principles ◽  
Quantum Dynamics ◽  
Chemical Processes ◽  
High Fidelity ◽  
Nonadiabatic Dynamics ◽  
Electronically Excited States ◽  
Electronically Excited ◽  
Oppenheimer Approximation

Nonadiabatic dynamics, which goes beyond the Born-Oppenheimer approximation, has increasingly been shown to play an important role in chemical processes, particularly those involving electronically excited states. Understanding multistate dynamics requires...

scholarly journals Nonadiabatic dynamics with quantum nuclei: simulating charge transfer with ring polymer surface hopping

2020 ◽  
Vol 221 ◽  
pp. 501-525 ◽  
Author(s):  
Soumya Ghosh ◽  
Samuele Giannini ◽  
Kevin Lively ◽  
Jochen Blumberger
Keyword(s):  
Charge Transfer ◽  
Polymer Surface ◽  
Nonadiabatic Dynamics ◽  
Surface Hopping ◽  
Different Temperatures ◽  
Ring Polymer ◽  
Adiabatic Dynamics

Exploring effects of quantizing nuclei in non-adiabatic dynamics for simulating charge transfer in a dimer of “ethylene-like-molecules” at different temperatures.

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

2018 ◽  
Vol 149 (24) ◽  
pp. 244107 ◽  
Author(s):  
Tianji Ma ◽  
Matteo Bonfanti ◽  
Pierre Eisenbrandt ◽  
Rocco Martinazzo ◽  
Irene Burghardt
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Complex ◽  
Nonadiabatic Dynamics ◽  
A Charge

scholarly journals X-ray transient absorption reveals the 1Au (nπ*) state of pyrazine in electronic relaxation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Valeriu Scutelnic ◽  
Shota Tsuru ◽  
Mátyás Pápai ◽  
Zheyue Yang ◽  
Michael Epshtein ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Nonadiabatic Dynamics ◽  
X Ray ◽  
Organic Chromophores ◽  
Dynamics Simulations ◽  
X Ray Absorption ◽  
Structure Calculations

AbstractElectronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized 1B2u (ππ*) (S2) and 1B3u (nπ*) (S1) states, the participation of the optically dark 1Au (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computations. Despite 1Au (nπ*) and 1B3u (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The 1Au (nπ*) state is populated in 200 ± 50 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

scholarly journals Modeling nonadiabatic dynamics with degenerate electronic states, intersystem crossing, and spin separation: A key goal for chemical physics

2021 ◽  
Vol 154 (11) ◽  
pp. 110901
Author(s):  
Xuezhi Bian ◽  
Yanze Wu ◽  
Hung-Hsuan Teh ◽  
Zeyu Zhou ◽  
Hsing-Ta Chen ◽  
...  
Keyword(s):  
Electronic States ◽  
Intersystem Crossing ◽  
Chemical Physics ◽  
Nonadiabatic Dynamics

scholarly journals Nonadiabatic Dynamics in Photodissociation of Hydroxymethyl in the 32A(3px) Rydberg State: A Nine-Dimensional Quantum Study

2019 ◽  
Vol 123 (10) ◽  
pp. 1937-1944 ◽  
Author(s):  
Changjian Xie ◽  
Christopher L. Malbon ◽  
Daiqian Xie ◽  
David R. Yarkony ◽  
Hua Guo
Keyword(s):  
Rydberg State ◽  
Nonadiabatic Dynamics
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