Toward ab initio molecular dynamics modeling for sum-frequency generation spectra; an efficient algorithm based on surface-specific velocity-velocity correlation function

2015 ◽  
Vol 143 (12) ◽  
pp. 124702 ◽  
Author(s):  
Tatsuhiko Ohto ◽  
Kota Usui ◽  
Taisuke Hasegawa ◽  
Mischa Bonn ◽  
Yuki Nagata
Keyword(s):  
Molecular Dynamics ◽  
Correlation Function ◽  
Ab Initio ◽  
Efficient Algorithm ◽  
Ab Initio Molecular Dynamics ◽  
Dynamics Modeling ◽  
Velocity Correlation ◽  
Sum Frequency ◽  
Molecular Dynamics Modeling ◽  
Velocity Correlation Function

Study on the Structure and Spectrum of Water in 1-Ethyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquids

2011 ◽  
Vol 271-273 ◽  
pp. 92-97
Author(s):  
Guo Cai Tian ◽  
Zhi Liang Jiao ◽  
Ya Dong Li
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Correlation Function ◽  
Ionic Liquids ◽  
Blue Shift ◽  
Water Molecules ◽  
Water Mixture ◽  
Velocity Correlation ◽  
Velocity Correlation Function ◽  
Dynamics Simulations

Various 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4)/water mixture with varying concentrations were studied by molecular dynamics simulations. The radial distribution function, the power spectrum velocity-velocity correlation function were calculated to reveal the microstructure and the IR spectrum. In both liquids, with the concentration of water in the mixture increase, the rotation bands and the bending bands of water are red shift whereas the O-H stretch bands are blue shift. It was found that the molecular rotation motions become slower as the proportion of water increases and water molecules tend to be isolated from each other in mixtures with more ions than water molecules. It was shown that water molecules tend to be isolated from each other in mixtures with more ions than water molecules in both liquids.

Combustion Driven by Fragment-based Ab Initio Molecular Dynamics Simulation

2019 ◽  
Author(s):  
Liqun Cao ◽  
Jinzhe Zeng ◽  
Mingyuan Xu ◽  
Chih-Hao Chin ◽  
Tong Zhu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Large Scale ◽  
Methane Combustion ◽  
Combustion Method ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Computational Time ◽  
Combustion Mechanism ◽  
Daily Lives

Combustion is a kind of important reaction that affects people's daily lives and the development of aerospace. Exploring the reaction mechanism contributes to the understanding of combustion and the more efficient use of fuels. Ab initio quantum mechanical (QM) calculation is precise but limited by its computational time for large-scale systems. In order to carry out reactive molecular dynamics (MD) simulation for combustion accurately and quickly, we develop the MFCC-combustion method in this study, which calculates the interaction between atoms using QM method at the level of MN15/6-31G(d). Each molecule in systems is treated as a fragment, and when the distance between any two atoms in different molecules is greater than 3.5 Å, a new fragment involved two molecules is produced in order to consider the two-body interaction. The deviations of MFCC-combustion from full system calculations are within a few kcal/mol, and the result clearly shows that the calculated energies of the different systems using MFCC-combustion are close to converging after the distance thresholds are larger than 3.5 Å for the two-body QM interactions. The methane combustion was studied with the MFCC-combustion method to explore the combustion mechanism of the methane-oxygen system.

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