Photo-induced isomerization of ethylene-bridged azobenzene explored by ab initio based non-adiabatic dynamics simulation: A comparative investigation of the isomerization in the gas and solution phases

2013 ◽  
Vol 138 (13) ◽  
pp. 134306 ◽  
Author(s):  
Jun Cao ◽  
Li-Hong Liu ◽  
Wei-Hai Fang ◽  
Zhi-Zhong Xie ◽  
Yong Zhang
Keyword(s):  
Ab Initio ◽  
Comparative Investigation ◽  
Dynamics Simulation ◽  
Adiabatic Dynamics

Non-adiabatic dynamics simulation exploration of the wavelength-dependent photoinduced relaxation mechanism of trans-N-1-methyl-2-(tolylazo) imidazole in the gas phase

RSC Advances ◽  
2016 ◽  
Vol 6 (69) ◽  
pp. 64323-64331 ◽  
Author(s):  
Li Zhao ◽  
Pan-Wang Zhou ◽  
Guang-Jiu Zhao
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Excited States ◽  
Relaxation Mechanism ◽  
Dynamics Simulation ◽  
Relaxation Dynamics ◽  
Surface Hopping ◽  
Electronic Excited States ◽  
Comprehensive Picture ◽  
Adiabatic Dynamics

A comprehensive picture of the photoinduced non-adiabatic relaxation dynamics of trans-N-1-methyl-2-(tolylazo) imidazole (trans-MTAI) in different electronic excited states has been revealed using the on-the-fly surface hopping method at the ab initio CASSCF level.

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.

Multiscale Analysis of Silicon LPCVD Reactor

2005 ◽  
Author(s):  
Yukinori Sakiyama ◽  
Shu Takagi ◽  
Yoichiro Matsumoto
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Multiscale Analysis ◽  
Potential Model ◽  
Research Work ◽  
Pair Potential ◽  
Dynamics Simulation ◽  
Molecular Orbital Calculations ◽  
Ongoing Research ◽  
Trajectory Calculations

We demonstrate the multiscale analysis of the transport phenomena in a low pressure reactor. In this method, the macroscopic phenomena such as the temperature and the density distribution are related to the microscopic electronic structure of atom/molecule. By connecting the different scales with physical models, the macroscopic properties are obtained starting from the first principle calculation without any empirical parameters. Here, we take the silicon epitaxial growth from a gas mixture of silane and hydrogen as an example. As the first step of this method, we calculated the intermolecular potential energy of SiH4/H2 using the ab initio molecular orbital calculations. Then, an analytical pair potential model was constructed to reproduce the potential energy surface obtained from the ab initio calculation. We have confirmed the validation of the potential model by comparing the experimental data of the transport properties with the molecular dynamics simulation using the potential model. Subsequently, the binary molecular collision models were constructed by the classical trajectory calculation using the potential model as the second step of the multiscale analysis. The trajectory calculations were conducted for the various combinations of the initial translational and the rotational energy. Through the statistical analysis of the trajectory calculations, the elastic/inelastic collision cross section and the scattering angle model were constructed. Finally, the direct simulation Monte Carlo simulation of flow field in a low parssure reactor was executed. The thin film thickness distribution was also investigated and discussed. This method was extended to analyze the surface reaction, which is an ongoing research work and only the current progress is reported here.

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