Molecular Dynamics Computer Simulation of Cooling Rate Effects in a Lennard-Jones Glass

1995 ◽  
pp. 117-121 ◽  
Author(s):  
K. Vollmayr ◽  
W. Kob ◽  
K. Binder
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Cooling Rate ◽  
Lennard Jones ◽  
Rate Effects

scholarly journals A variational approach to nucleation simulation

2016 ◽  
Vol 195 ◽  
pp. 557-568 ◽  
Author(s):  
Pablo M. Piaggi ◽  
Omar Valsson ◽  
Michele Parrinello
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Free Energy ◽  
Variational Approach ◽  
Sampling Method ◽  
Enhanced Sampling ◽  
Technical Problems ◽  
Lennard Jones ◽  
Dynamics Simulations

We study by computer simulation the nucleation of a supersaturated Lennard-Jones vapor into the liquid phase. The large free energy barriers to transition make the time scale of this process impossible to study by ordinary molecular dynamics simulations. Therefore we use a recently developed enhanced sampling method [Valsson and Parrinello, Phys. Rev. Lett.113, 090601 (2014)] based on the variational determination of a bias potential. We differ from previous applications of this method in that the bias is constructed on the basis of the physical model provided by the classical theory of nucleation. We examine the technical problems associated with this approach. Our results are very satisfactory and will pave the way for calculating the nucleation rates in many systems.

scholarly journals Cooling-rate effects in amorphous silica: A computer-simulation study

1996 ◽  
Vol 54 (22) ◽  
pp. 15808-15827 ◽  
Author(s):  
Katharina Vollmayr ◽  
Walter Kob ◽  
Kurt Binder
Keyword(s):  
Computer Simulation ◽  
Cooling Rate ◽  
Simulation Study ◽  
Amorphous Silica ◽  
Computer Simulation Study ◽  
Rate Effects

Molecular Dynamics Computer Simulation of the Rupture of the two - Dimensional Lennard - Jones Film

1990 ◽  
Vol 188 ◽  
Author(s):  
John F. Maguire ◽  
Chun- Pok Leung
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Tensile Failure ◽  
Dynamical Response ◽  
Two Dimensional ◽  
Lennard Jones ◽  
Random Forces ◽  
Internal Stress Field ◽  
Defect Nucleation ◽  
Reduced Temperature

ABSTRACTWe have conducted a molecular dynamics computer simulation of the rupture of a small, two-dimensional film. The film was composed of two hundred atoms arranged on a close-packed triangular lattice and was thermally equilibrated at a reduced temperature of 0.05. Following equilibration, the rupture characteristics of the film were investigated under tensile loading, and the atomistic dynamical response was followed throughout the rupture process. An estimate of the internal stress field was made by performing a time average over the random forces. In tensile failure, the system undergoes an initial elastic deformation followed by plastic flow. The fundamental mechanisms of defect nucleation are briefly discussed.

Formation of Polyelectrolyte Brushes on Plate

2013 ◽  
Vol 749 ◽  
pp. 588-590
Author(s):  
Yang Yang ◽  
Chun Cheng Zuo ◽  
Yu Xin Zuo ◽  
Ying Yu
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Positive Charge ◽  
Coarse Grained ◽  
Lennard Jones Potential ◽  
Molecular Models ◽  
Jones Potential ◽  
Polyelectrolyte Brushes ◽  
Lennard Jones ◽  
Adsorption Density

The adsorption of polyelectrolyte chains on plate are studied using coarse-grained, bead-spring molecular models and Molecular dynamics computer simulation. It has been applied for studying the formation of polyelectrolyte brushes confined in the plates via the Lennard-Jones potential. The simulation result shows that the polyelectrolyte chains adsorption density is strongly affected by the length of the block carries the positive charge. Correspondingly, the counterions are added to the system. Upon changing the polyelectrolyte chain length N from 8 to 48, the profile of adsorption density decline between N=8 to N=18, and then rise. It has a minimum at N=18.These initial findings can be used as a guide for the preparation of actual polyelectrolyte brushes on plate by the adsorption approach.

scholarly journals COOLING RATE DEPENDENCE AND DYNAMIC HETEROGENEITY BELOW THE GLASS TRANSITION IN A LENNARD–JONES GLASS

1999 ◽  
Vol 10 (08) ◽  
pp. 1443-1451 ◽  
Author(s):  
K. VOLLMAYR-LEE ◽  
W. KOB ◽  
K. BINDER ◽  
A. ZIPPELIUS
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Cooling Rate ◽  
Melting Process ◽  
Rate Dependence ◽  
Local Order ◽  
Average Particle ◽  
Dynamic Heterogeneity ◽  
Lennard Jones ◽  
Dynamics Simulations

We investigate a binary Lennard–Jones mixture with molecular dynamics simulations. We consider first a system cooled linearly in time with the cooling rate γ. By varying γ over almost four decades we study the influence of the cooling rate on the glass transition and on the resulting glass. We find for all investigated quantities a cooling rate dependence; with decreasing cooling rate the system falls out of equilibrium at decreasing temperatures, reaches lower enthalpies and obtains increasing local order. Next we study the dynamics of the melting process by investigating the most immobile and most mobile particles in the glass. We find that their spatial distribution is heterogeneous and that the immobile/mobile particles are surrounded by denser/less dense cages than an average particle.

scholarly journals Molecular Dynamics of the Phase Transition in Compressible Ammonium Chloride

1984 ◽  
Vol 37 (6) ◽  
pp. 667
Author(s):  
Sadhana Pandey ◽  
SK Trikha
Keyword(s):  
Phase Transition ◽  
Molecular Dynamics ◽  
Computer Simulation ◽  
High Pressure ◽  
Raman Spectrum ◽  
Ammonium Chloride ◽  
Dynamical Behaviour ◽  
Lennard Jones ◽  
Nearest Neighbours ◽  
Computer Simulation Technique

The effects of pressure on the dynamical behaviour of an NH: ion near the A transition under the influence of its nearest neighbours in ammonium chloride have been studied by using the computer simulation technique. The Lennard Jones (6-12) potential is used as the representative interaction between NH: and Cl-. The present calculations reveal a decrease in entropy of the system with increasing pressure. The libration frequency of the NH: ion is estimated to be approximately 170, 182 and 210 cm -1 at pressures of 1 atm, 3 and 10 kbar respectively, in agreement with the Raman spectrum study of NH4CI at high pressure (Ebisuzaki and Nicol 1969).

Computer Simulation of Laser-Induced Ultrarapid Phase Changes

1988 ◽  
Vol 100 ◽  
Author(s):  
Myron T. Maclin ◽  
Michael J. Sabochick ◽  
James P. Mills
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Phase Change ◽  
Phase Changes ◽  
Analytical Models ◽  
Change Models ◽  
Lennard Jones ◽  
Analytical Phase ◽  
Molecular Dynamics Results

ABSTRACTThe results of a molecular dynamics study of phase change in a system of condensed Lennard-Jones atoms is presented. These molecular dynamics results are compared to the rates of phase change predicted by two analytical phase change models. Both analytical models are supported by the molecular dynamics results.

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