A First Model of Amorphous GaN from Ab Initio Molecular Dynamics

1996 ◽  
Vol 449 ◽  
Author(s):  
D. A. Drabold ◽  
Petra Stumm
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Ab Initio ◽  
Density Of States ◽  
Vibrational Spectra ◽  
Structural Model ◽  
Ab Initio Molecular Dynamics ◽  
Electronic Density ◽  
Optical Gap ◽  
Local Bonding

ABSTRACTA probable byproduct of growth of crystalline GaN is an amorphous phase of the material. In this paper, we propose a structural model of amorphous GaN obtained from ah initio molecular dynamics. The radial distribution function, local bonding, electronic density of states and vibrational spectra are described. The network we obtain is highly disordered but exhibits a large state-free optical gap, and has no wrong (homopolar) bonds. These predictions are intended to elucidate the experimental signatures of amorphous GaN.

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.

Ab Initio Molecular Dynamics Study of Al, Ga and Si Adsorption on the Si(001) Surface

1993 ◽  
Vol 318 ◽  
Author(s):  
T. Yamasaki ◽  
M. Ikeda ◽  
Y. Morikawa ◽  
K. Terakura
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Density Of States ◽  
Local Density ◽  
Ab Initio Molecular Dynamics ◽  
Local Density Of States ◽  
Mono Layer ◽  
The Difference ◽  
Stable Structures

ABSTRACTThe adsorption of Al, Ga and Si on the Si(001) surface is studied by the ab initio molecular dynamics (Car-Parrinello) method based on the norm-conserving pseudopotential. In the stable structures obtained for half mono-layer coverage( ө = 1/2), these ad-atoms form dimers, but the dimer configurations are different. Al and Ga atoms form parallel dimers whose dimerization direction is parallel to that of substrate Si-dimers, while adsorbed Si atoms form (dense) orthogonal dimers. The electronic origin of the difference in the stable configurations among Al, Ga and Si ad-atoms is analyzed by calculating the local density of states (LDOS) of each atom.

Ab Initio Molecular Dynamics of Column IV Microclusters

1990 ◽  
Vol 193 ◽  
Author(s):  
David A. Drabold ◽  
Stefan Klemm ◽  
Otto F. Sankey
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Vibrational Spectra ◽  
Ground State ◽  
Spectral Estimation ◽  
Ab Initio Molecular Dynamics ◽  
Estimation Technique ◽  
Dynamics Simulations ◽  
Small Clusters

ABSTRACTWe report the results of ab-initio molecular dynamics simulations for small clusters of Si and C atoms. Ground-state geometries and vibrational spectra are presented. We also describe a Bayesian spectral estimation technique which we have found to be useful in analyzing molecular dynamics trajectories.

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