Application of a Classical Force Field for Polyvinylchloride Derived from Ab initio Calculations.

1990 ◽  
Vol 215 ◽  
Author(s):  
Peter J. Ludovice ◽  
Richard L. Jaffe ◽  
Do Y. Yoon
Keyword(s):  
Force Field ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Mechanics ◽  
Stochastic Dynamics ◽  
Atomic Level ◽  
Model Compounds ◽  
Dynamics Simulations ◽  
Energy Surfaces

AbstractAb initio calculations were used to characterize the inter- and intramolecular energy surfaces for polyvinylchloride (PVC) model compounds and a classical force field was fit to these energy surfaces. This new force field will be used in molecular mechanics and stochastic dynamics simulations to analyze the atomic level morphology of PVC.

Millimetre-wave and infrared spectroscopy of Br13 CN: anharmonic force field of cyanogen bromide from spectroscopic data and ab initio calculations

1997 ◽  
Vol 90 (3) ◽  
pp. 495-497
Author(s):  
CLAUDIO ESPOSTI ◽  
FILIPPO TAMASSIA ◽  
CRISTINA PUZZARINI ◽  
RICCARDO TARRONI ◽  
ZDENEK ZELINGER
Keyword(s):  
Infrared Spectroscopy ◽  
Force Field ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Spectroscopic Data ◽  
Cyanogen Bromide ◽  
Millimetre Wave ◽  
Anharmonic Force

Active Learning Accelerates Ab Initio Molecular Dynamics on Pericyclic Reactive Energy Surfaces

2020 ◽  
Author(s):  
Shi Jun Ang ◽  
Wujie Wang ◽  
Daniel Schwalbe-Koda ◽  
Simon Axelrod ◽  
Rafael Gomez-Bombarelli
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Transition State ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Cost ◽  
Reactive Trajectories ◽  
Dynamics Simulations ◽  
Energy Surfaces

<div>Modeling dynamical effects in chemical reactions, such as post-transition state bifurcation, requires <i>ab initio</i> molecular dynamics simulations due to the breakdown of simpler static models like transition state theory. However, these simulations tend to be restricted to lower-accuracy electronic structure methods and scarce sampling because of their high computational cost. Here, we report the use of statistical learning to accelerate reactive molecular dynamics simulations by combining high-throughput ab initio calculations, graph-convolution interatomic potentials and active learning. This pipeline was demonstrated on an ambimodal trispericyclic reaction involving 8,8-dicyanoheptafulvene and 6,6-dimethylfulvene. With a dataset size of approximately</div><div>31,000 M062X/def2-SVP quantum mechanical calculations, the computational cost of exploring the reactive potential energy surface was reduced by an order of magnitude. Thousands of virtually costless picosecond-long reactive trajectories suggest that post-transition state bifurcation plays a minor role for the reaction in vacuum. Furthermore, a transfer-learning strategy effectively upgraded the potential energy surface to higher</div><div>levels of theory ((SMD-)M06-2X/def2-TZVPD in vacuum and three other solvents, as well as the more accurate DLPNO-DSD-PBEP86 D3BJ/def2-TZVPD) using about 10% additional calculations for each surface. Since the larger basis set and the dynamic correlation capture intramolecular non-covalent interactions more accurately, they uncover longer lifetimes for the charge-separated intermediate on the more accurate potential energy surfaces. The character of the intermediate switches from entropic to thermodynamic upon including implicit solvation effects, with lifetimes increasing with solvent polarity. Analysis of 2,000 reactive trajectories on the chloroform PES shows a qualitative agreement with the experimentally-reported periselectivity for this reaction. This overall approach is broadly applicable and opens a door to the study of dynamical effects in larger, previously-intractable reactive systems.</div>

Intermolecular potential energy surfaces and spectra of Ne–HCN complex from ab initio calculations

2001 ◽  
Vol 114 (2) ◽  
pp. 764 ◽  
Author(s):  
Garold Murdachaew ◽  
Alston J. Misquitta ◽  
Robert Bukowski ◽  
Krzysztof Szalewicz
Keyword(s):  
Potential Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Intermolecular Potential ◽  
Energy Surfaces
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