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 Approach to the Study of Grain Boundaries in Semiconductors

1988 ◽  
Vol 141 ◽  
Author(s):  
E. Tarnow ◽  
P. D. Bristowe ◽  
J. D. Joannopoulos ◽  
M. C. Payne
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Ab Initio ◽  
Local Density ◽  
Ab Initio Molecular Dynamics ◽  
Local Density Of States ◽  
High Angle ◽  
Surface Information ◽  
Atomic And Electronic Structure ◽  
Translation State

AbstractUsing an ab-initio molecular dynamics approach based on the Car-Parrinello method, the detailed atomic and electronic structure of a high-angle grain boundary in germanium is determined by investigating its energy-translation surface. Information concerning the coordination of the lowest energy configuration, its translation state, volume change, structure factor and local density of states is obtained.

MODIFICATION OF CASIMIR FORCES DUE TO BAND GAPS IN PERIODIC STRUCTURES

2002 ◽  
Vol 17 (06n07) ◽  
pp. 798-803 ◽  
Author(s):  
C. VILLARREAL ◽  
R. ESQUIVEL-SIRVENT ◽  
G. H. COCOLETZI
Keyword(s):  
Density Of States ◽  
Casimir Force ◽  
Periodic Structures ◽  
Local Density ◽  
Band Gaps ◽  
Basic Unit ◽  
Local Density Of States ◽  
Casimir Forces ◽  
Unit Cells ◽  
The Difference

The Casimir force between inhomogeneous slabs that exhibit a band-like structure is calculated. The slabs are made of basic unit cells each made of two layers of different materials. As the number of unit cells increases the Casimir force between the slabs changes, since the reflectivity develops a band-like structure characterized by frequency regions of high reflectivity. This is also evident in the difference of the local density of states between free and boundary distorted vacuum, that becomes maximum at frequencies corresponding to the band gaps. The calculations are restricted to vacuum modes with wave vectors perpendicular to the slabs.

AB-INITIO MOLECULAR DYNAMICS IN THE FULL-POTENTIAL LMTO METHOD: DERIVATION OF A PRACTICAL FORCE THEOREM

1993 ◽  
Vol 07 (01n03) ◽  
pp. 262-265 ◽  
Author(s):  
M. METHFESSEL ◽  
M. VAN SCHILFGAARDE
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Local Density ◽  
Basis Set ◽  
Ab Initio Molecular Dynamics ◽  
Basis Sets ◽  
Full Potential ◽  
Major Advance ◽  
First Results ◽  
Lmto Method

A major advance in electronic structure calculations was the combination of local-density techniques with molecular dynamics by Car and Parrinello seven years ago. Unfortunately, application of the Car-Parrinello scheme has been limited essentially to sp materials because only in the plane-wave pseudopotential method forces are trivial to calculate. We present a systematic approach to derive force theorems with desired characteristics within complicated basis sets, which are applicable to all elements of the periodic table equally well. Application to the LMTO basis set yields an accurate force theorem, quite distinct from the Hellman-Feynman form, which is exceptionally insensitive to errors in the trial density. The forces were implemented in a new full-potential LMTO method which is suited to arbitrary geometries. First results for ab-initio molecular dynamics and simulated annealing runs are shown for some random small molecules and small clusters of silver atoms.

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.

scholarly journals Ab Initio Molecular Dynamics Study of the Structure and Properties of Nb-Doped Zr-Cu-Al Amorphous Alloys

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1821
Author(s):  
Hongqing Wei ◽  
Ping Zhang ◽  
Yi Tang
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Amorphous Alloys ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Structure And Properties ◽  
Stable Clusters ◽  
Macroscopic Plasticity ◽  
The Stability ◽  
Stable Structures

In this paper, experiments were carried out on (Zr0.5Cu0.4Al0.1)100-xNbx (x = 0, 3, 6 at.%) amorphous alloys, and the corresponding ab initio molecular dynamics simulation was performed. The results showed that stable structures of Nb-centered and Al-centered icosahedral (-like) atomic clusters were formed after a small amount of (3 at.%) Nb was added. Stable and close-packed backbone structures were formed by the means of interconnection and matching of the two kinds of stable clusters in the alloys, which also enhanced the overall heterogeneity of the structures, thereby improving the strength and macroscopic plasticity. In addition, when more (6 at.%) Nb was added, the stable Al-centered clusters were replaced by some stable Nb-centered clusters in the alloys, and the stability and heterogeneity of the structures were partly reduced, which reduced the strength and macroscopic plasticity.

scholarly journals Density of States Broadening in CH3NH3PbI3 Hybrid Perovskites Understood from ab Initio Molecular Dynamics Simulations

2018 ◽  
Vol 3 (4) ◽  
pp. 787-793 ◽  
Author(s):  
Liujiang Zhou ◽  
Amanda J. Neukirch ◽  
Dayton J. Vogel ◽  
Dmitri S. Kilin ◽  
Laurent Pedesseau ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Density Of States ◽  
Ab Initio Molecular Dynamics ◽  
Dynamics Simulations
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