scholarly journals Adaptive Variational Quantum Dynamics Simulations

PRX Quantum ◽  
2021 ◽  
Vol 2 (3) ◽  
Author(s):  
Yong-Xin Yao ◽  
Niladri Gomes ◽  
Feng Zhang ◽  
Cai-Zhuang Wang ◽  
Kai-Ming Ho ◽  
...  
Keyword(s):  
Quantum Dynamics ◽  
Dynamics Simulations

scholarly journals Investigating Tunneling Controlled Chemical Reactions Through Ab-Initio Ring Polymer Molecular Dynamics

2021 ◽  
Author(s):  
Xinyang Li ◽  
Pengfei Huo
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Chemical Reaction ◽  
Quantum Tunneling ◽  
Quantum Dynamics ◽  
Density Functional ◽  
Molecular System ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Dynamics Simulations

<div>We use the ab-initio ring polymer molecular dynamics (RPMD) approach to investigate tunneling controlled reactions in methylhydroxycarbene. Nuclear tunneling effects enable molecules to overcome the barriers which can not be overcome classically. Under low-temperature conditions, intrinsic quantum tunneling effects canfacilitate the chemical reaction in a pathway that is neither favored thermodynamically nor kinetically. This</div><div>behavior is referred to as the tunneling controlled chemical reaction and regarded as the third paradigm of chemical</div><div>reaction controls. In this work, we use the ab-initio RPMD approach to incorporate the tunneling effects in our quantum dynamics simulations. The reaction kinetics of two competitive reaction pathways at various temperatures are investigated with the Kohn-Sham density functional theory (KS-DFT) on-the-fly molecular dynamics simulations and the ring polymer quantization of the nuclei. The reaction rate constants obtained here agree extremely well with the experimentally measured rates. We demonstrate the feasibility of using ab-initio RPMD rate calculations in a realistic molecular system, and provide an interesting and important example for future investigations on reaction mechanisms dominated by quantum tunneling effects.</div>

scholarly journals Micro-Solvated DMABN: Excited State Quantum Dynamics and Dual Fluorescence Spectra

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7247
Author(s):  
Sandra Gómez ◽  
Esra N. Soysal ◽  
Graham A. Worth
Keyword(s):  
Electronic Structure ◽  
Excited State ◽  
Quantum Dynamics ◽  
Computational Study ◽  
Water Solution ◽  
Fluorescence Emission ◽  
Spectroscopic Properties ◽  
Complete Analysis ◽  
Solvent Molecules ◽  
Dynamics Simulations

In this work, we report a complete analysis by theoretical and spectroscopic methods of the short-time behaviour of 4-(dimethylamino)benzonitrile (DMABN) in the gas phase as well as in cyclohexane, tetrahydrofuran, acetonitrile, and water solution, after excitation to the La state. The spectroscopic properties of DMABN were investigated experimentally using UV absorption and fluorescence emission spectroscopy. The computational study was developed at different electronic structure levels and using the Polarisable Continuum Model (PCM) and explicit solvent molecules to reproduce the solvent environment. Additionally, excited state quantum dynamics simulations in the diabatic picture using the direct dynamics variational multiconfigurational Gaussian (DD-vMCG) method were performed, the largest quantum dynamics “on-the-fly” simulations performed with this method until now. The comparison with fully converged multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) dynamics on parametrised linear vibronic coupling (LVC) potentials show very similar population decays and evolution of the nuclear wavepacket. The ring C=C stretching and three methyl tilting modes are identified as the responsible motions for the internal conversion from the La to the Lb states. No major differences are observed in the ultrafast initial decay in different solvents, but we show that this effect depends strongly on the level of electronic structure used.

scholarly journals Curve crossing in a manifold of coupled electronic states: direct quantum dynamics simulations of formamide

2018 ◽  
Vol 212 ◽  
pp. 191-215 ◽  
Author(s):  
K. Eryn Spinlove ◽  
Gareth W. Richings ◽  
Michael A. Robb ◽  
Graham A. Worth
Keyword(s):  
Quantum Dynamics ◽  
Organic Molecules ◽  
Potential Surface ◽  
Electronic States ◽  
Small Organic Molecules ◽  
Direct Dynamics ◽  
Dynamics Simulations ◽  
Curve Crossing

Fully quantum direct dynamics simulations generate the potential surface manifold for the photo-excited dynamics of small organic molecules.

Competition between the heavy atom effect and vibronic coupling in donor–bridge–acceptor organometallics

2020 ◽  
Vol 22 (8) ◽  
pp. 4659-4667 ◽  
Author(s):  
Julien Eng ◽  
Stuart Thompson ◽  
Heather Goodwin ◽  
Dan Credgington ◽  
Thomas James Penfold
Keyword(s):  
Excited State ◽  
Quantum Dynamics ◽  
Heavy Atom ◽  
Vibronic Coupling ◽  
Intersystem Crossing ◽  
Heavy Atom Effect ◽  
Metal Amides ◽  
Coinage Metals ◽  
Dynamics Simulations ◽  
Atom Effect

The excited state properties and intersystem crossing dynamics of a series of donor–bridge–acceptor carbene metal-amides based upon the coinage metals Cu, Ag, Au, are investigated using quantum dynamics simulations and supported by photophysical characterisation.

Quantum dynamics simulations using Gaussian wavepackets: the vMCG method

2015 ◽  
Vol 34 (2) ◽  
pp. 269-308 ◽  
Author(s):  
G.W. Richings ◽  
I. Polyak ◽  
K.E. Spinlove ◽  
G.A. Worth ◽  
I. Burghardt ◽  
...  
Keyword(s):  
Quantum Dynamics ◽  
Dynamics Simulations
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