Vibrational spectra and molecular dynamics of 1,2-di-(p-XC6H4)ethanes (X=Br,NO2)

2001 ◽  
Author(s):  
D. I. Kamalova ◽  
S. A. Petrova ◽  
A. B. Remizov ◽  
R. A. Skochilov
Keyword(s):  
Molecular Dynamics ◽  
Vibrational Spectra

Structural stabilities and transformations in cationized asparagine at finite temperatures: An ab initio molecular dynamics study

2014 ◽  
Vol 13 (04) ◽  
pp. 1450024
Author(s):  
Shoutian Sun ◽  
Jianwen Liu ◽  
Zhi-Feng Liu
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Structural Transformation ◽  
Vibrational Spectra ◽  
Room Temperature ◽  
Ab Initio Molecular Dynamics ◽  
And Shifts ◽  
Torsional Angles

The cationic complexes of Asparagine (Asn), M +( Asn ), with M + = Li +, Na +, K +, Cs +, and H +, are models for studying the interaction between cations and Asn. Ab initio molecular dynamics (AIMD) method is employed to simulate their behavior at finite temperatures. Structural transformation between conformers is observed, which becomes progressively easier as the cation varies from Li +, to Na +, K +, Cs +, and H +. The fluctuation of the M +– N and M +– O distances and rotation of torsional angles are significant even at room temperature for K +, Cs + and H +. Vibrational profiles based on AIMD trajectories provide insights into the broadening and shifts in relative intensities observed in the vibrational spectra measured by infrared multi-photon dissociation (IRMPD) experiments.

A Theoretical Study Of The Energetics And Vibrational Spectra Of Oxygenated (100) Diamond Surfaces

1995 ◽  
Vol 416 ◽  
Author(s):  
S. Skokov ◽  
B. Weiner ◽  
M. Frenklach
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Vibrational Spectra ◽  
Theoretical Study ◽  
Local Environment ◽  
Hydroxyl Groups ◽  
Vibrational Modes ◽  
Diamond Surfaces ◽  
Molecular Dynamics Calculations

ABSTRACTStatic quantum ab initio and quantum semiempirical molecular dynamics calculations were employed to study reconstructions of (100) diamond surfaces in presence of hydrogen and oxygen. The results indicate that the energetically most favorable structures of oxygenated surfaces are those with chemisorbed hydroxyl groups. It was found that hydrogen bonds are formed among chemisorbed oxygenated species. The formation of these hydrogen bonds is shown to be an important factor in stabilization of adlayers. A number of important vibrational modes characteristic of oxygenated diamond surfaces were identified. The analysis of surface vibrational spectra demonstrates the influence of the local environment on the position of vibrational modes and can be useful for interpretation of experimental data.

scholarly journals Molecular dynamics with constrained nuclear electronic orbital density functional theory: Accurate vibrational spectra from efficient incorporation of nuclear quantum effects

2021 ◽  
Author(s):  
Xi Xu ◽  
Zehua Chen ◽  
Yang Yang
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Molecular Simulations ◽  
Quantum Effects ◽  
Functional Theory ◽  
Chemical And Biological Systems ◽  
Nuclear Quantum Effects ◽  
Orbital Density

Nuclear quantum effects play a crucial role in many chemical and biological systems involving hydrogen atoms yet are difficult to include in practical molecular simulations. In this Letter, we combine our recently developed methods of constrained nuclear-electronic orbital density functional theory (cNEO-DFT) and constrained minimized energy surface molecular dynamics (CMES-MD) to create a new method for accurately and efficiently describing nuclear quantum effects in molecular simulations. Using this new method, dubbed cNEO-MD, the vibrational spectra of a set of small molecules are calculated and compared with those from conventional ab initio molecular dynamics (AIMD) as well as from experiments. With the same formal scaling, cNEO-MD greatly outperforms AIMD in describing the vibrational modes with significant hydrogen motion characters, demonstrating the promise of cNEO-MD for simulating chemical and biological systems with significant nuclear quantum effects.

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