Molecular Dynamics Simulations of Porous Silica

1997 ◽  
Vol 492 ◽  
Author(s):  
J.V.L. Beckers ◽  
S. W. De Leeuw
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Porous Silica ◽  
Power Spectra ◽  
Low Frequency ◽  
Internal Surface ◽  
Simulation Method ◽  
Porous Network ◽  
Long Range Correlations ◽  
Dynamics Simulations

ABSTRACTWe describe a new simulation method for the preparation of porous silica and present results from molecular dynamics simulations of the structures obtained. We start from a homogeneous liquid phase with reduced atomic charges. The charges are then slowly rescaled and the atoms start clustering to finally form a porous network. We observe that local ordering precedes formation of long range correlations. We investigate physical properties of porous silica such as porosity, internal surface and fractality. They are in reasonable agreement with experimental data, although internal surface and porosity seem to be systematically larger than those found in adsorption experiments. The vibrational and dielectric power spectra show an enhanced intensity in the low frequency region. These modes can be associated with slow dynamics of clusters.

Local order and long range correlations in imidazolium halide ionic liquids: a combined molecular dynamics and XAS study

2015 ◽  
Vol 17 (25) ◽  
pp. 16443-16453 ◽  
Author(s):  
Valentina Migliorati ◽  
Alessandra Serva ◽  
Giuliana Aquilanti ◽  
Sakura Pascarelli ◽  
Paola D'Angelo
Keyword(s):  
Molecular Dynamics ◽  
Ionic Liquids ◽  
Molecular Dynamics Simulations ◽  
Long Range ◽  
Exafs Spectroscopy ◽  
Local Order ◽  
Long Range Correlations ◽  
Long Range Interactions ◽  
Dynamics Simulations

EXAFS spectroscopy and molecular dynamics simulations have been combined to unveil the effect of the cation and anion nature on the local order and long range interactions of imidazolium halide ionic liquids.

Molecular Dynamics Simulations of Hot Electrons and Lattice Relaxation in Realistic Cascade Volumes

1992 ◽  
Vol 278 ◽  
Author(s):  
A.M. Mazzone
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Molecular Dynamics Simulations ◽  
Classical Mechanics ◽  
Lattice Relaxation ◽  
Simulation Method ◽  
High Energy ◽  
Hot Electrons ◽  
Dynamics Simulation ◽  
Dynamics Simulations

AbstractThis work presents a molecular dynamics simulation method designed to describe the processes of electron and lattice relaxation taking place in typical cascade volumes formed by high-energy implants. The simulation method is based on classical mechanics and includes the motions of electrons and nuclei. The results are in agreement with experiments.

Mass Transport in Nanoalloys Studied by Atomistic Models

2017 ◽  
Vol 12 ◽  
pp. 23-37 ◽  
Author(s):  
Riccardo Ferrando
Keyword(s):  
Molecular Dynamics ◽  
Mass Transport ◽  
Molecular Dynamics Simulations ◽  
Gas Phase ◽  
Metallic Nanoparticles ◽  
Simulation Method ◽  
Impurity Atoms ◽  
Atomistic Models ◽  
Dynamics Simulations ◽  
Small Nanoparticles

The diffusion of atoms in nanoparticles can be studied computationally by Molecular Dynamics simulations, a simulation method which allow to follow the actual trajectories of the diffusing atoms. Here we focus on the simulation of diffusion in metallic nanoparticles, first considering the case of single impurity atoms in matrix clusters, and then on the simulation of the growth in gas phase. We show that diffusion of atoms in nanoparticles can take place by a variety of different mechanisms, which very often involve collective displacements. These collective displacements are facilitated in the vicinity of the cluster surface, which, in small nanoparticles, includes a large portion of the nanoparticle itself.

Molecular Dynamics Simulations of Low-Energy Atom-Surface Interactions

1992 ◽  
Vol 268 ◽  
Author(s):  
J. A. Sprague ◽  
C. M. Gilmore
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Film Growth ◽  
Low Frequency ◽  
Exchange Interactions ◽  
Low Energy ◽  
Growth Surface ◽  
Surface Exchange ◽  
Oriented Film ◽  
Dynamics Simulations

ABSTRACTMolecular dynamics simulations of the deposition of atoms on crystalline surfaces have been conducted using the embedded atom method. The following atom-substrate combinations have been employed: 0.1 - 40 eV Ag deposited on (111) and (100) Ag substrates; 0.1 eV Ag deposited on (100) Cu; and 0.1 eV Cu deposited on (100) Ag. The purpose of the calculations for Ag atoms deposited on Ag substrates was to investigate the effects of adatom arrival energy and substrate orientation on the interactions of low-energy atoms with crystal surfaces. The goal of tile Ag oil Cu and Cu on Ag calculations was to observe the mechanisms producing thepreviously-reported asymmetry in epitaxy for these systems. The Ag on Ag deposition simulations demonstrated that the effects of increased atom arrival energies in promoting layerby- layer film growth and producing diffuse substrate-filn interfaces (mixing) were basically the same on the (100) and (111) surfaces. At 0. 1 eV, representative of thennal evaporation, the degree of island formation on the (100) substrate was essentially tile same as previously reported for a (111) Ag substrate. At a given atom arrival energy between 10 and 40 eV, both the redistribution into full monolayers and the mixing by surface exchange interactions were seen to occur more readily on the close-packed (111) growth surface than on the more open (100) surface. The mixing was a stronger function of crystallographic orientation. Cu was observed to grow on (100) Ag as a (100)-oriented film, with the initial film layers transfonned essentially to the bcc structure by a Bain distortion, in agreement with various experimental results. The distortion of the film layers resulted in large-amplitude soft-mode (low-frequency) lattice vibrations. Ag was observed to grow on (100) Cu as a (111)-oriented film, as experimentally observed, with the <110>-type orientations of film and substrate parallel, as predicted by previous calculations of interfacial energy.

scholarly journals Molecular Dynamics Simulations on Influence of Defect on Thermal Conductivity of Silicon Nanowires

2021 ◽  
Vol 9 ◽  
Author(s):  
Hao Li ◽  
Qiancheng Rui ◽  
Xiwen Wang ◽  
Wei Yu
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Silicon Nanowires ◽  
Surface Defects ◽  
Low Frequency ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations ◽  
The Impact

A non-equilibrium molecular dynamics simulation method is conducted to study the thermal conductivity (TC) of silicon nanowires (SiNWs) with different types of defects. The impacts of defect position, porosity, temperature, and length on the TC of SiNWs are analyzed. The numerical results indicate that SiNWs with surface defects have higher TC than SiNWs with inner defects, the TC of SiNWs gradually decreases with the increase of porosity and temperature, and the impact of temperature on the TC of SiNWs with defects is weaker than the impact on the TC of SiNWs with no defects. The TC of SiNWs increases as their length increases. SiNWs with no defects have the highest corresponding frequency of low-frequency peaks of phonon density of states; however, when SiNWs have inner defects, the lowest frequency is observed. Under the same porosity, the average phonon participation of SiNWs with surface defects is higher than that of SiNWs with inner defects.

Mechanics of Nanostructured Porous Silica Aerogel Resulting from Molecular Dynamics Simulations

2017 ◽  
Vol 121 (22) ◽  
pp. 5660-5668 ◽  
Author(s):  
Sandeep P. Patil ◽  
Ameya Rege ◽  
Sagardas ◽  
Mikhail Itskov ◽  
Bernd Markert
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Silica Aerogel ◽  
Porous Silica ◽  
Dynamics Simulations
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