AB INITIO PATH INTEGRAL STUDY ON ISOTOPE EFFECT OF AMMONIA MOLECULE

2005 ◽  
Vol 04 (01) ◽  
pp. 175-181 ◽  
Author(s):  
MASANORI TACHIKAWA ◽  
MOTOYUKI SHIGA
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Isotope Effect ◽  
Path Integral ◽  
Quantum Chemical ◽  
Degrees Of Freedom ◽  
Dynamics Simulation ◽  
Ammonia Molecule ◽  
Quantum Chemical Approach ◽  
Quantum Feature

We have applied ab initio path integral molecular dynamics simulation to study the quantum feature and proton/deuteron isotope effect of ammonia molecule. This method treats all the rotational and vibrational degrees of freedom fully quantum mechanically, while the potential energies of the respective molecular configurations are calculated "on the fly" using ab initio quantum chemical approach. The differences on the geometry and the electronic structure between NH 3 and ND 3 molecules are investigated in detail.

Geometric Isotope Effect on the N2H7+ Cation and N2H5− Anion by Ab Initio Path Integral Molecular Dynamics Simulation

ChemPhysChem ◽  
2008 ◽  
Vol 9 (3) ◽  
pp. 383-387 ◽  
Author(s):  
Hiroaki Ishibashi ◽  
Aiko Hayashi ◽  
Motoyuki Shiga ◽  
Masanori Tachikawa
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Ab Initio ◽  
Isotope Effect ◽  
Path Integral ◽  
Dynamics Simulation

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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