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.

Surface Tension Evaluation Via Thermodynamic Analysis of Statistical Data From Molecular Dynamics Simulations

Volume 4 ◽  
2004 ◽  
Author(s):  
Aaron P. Wemhoff ◽  
Van P. Carey
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Density Profile ◽  
Md Simulation ◽  
Md Simulations ◽  
Bulk Liquid ◽  
Interfacial Region ◽  
Lennard Jones Potential ◽  
Jones Potential ◽  
Lennard Jones

Surface tension determination of liquid-vapor interfaces of polyatomic fluids using traditional methods has shown to be difficult due to the requirement of evaluating complex intermolecular potentials. However, analytical techniques have recently been developed that determine surface tension solely by means of the characteristics of the interfacial region between the bulk liquid and vapor regions. A post-simulation application of the excess free energy density integration (EFEDI) method was used for analysis of the resultant density profile of molecular dynamics (MD) simulations of argon using a simple Lennard-Jones potential and diatomic nitrogen using a two-center Lennard-Jones potential. MD simulations were also run for an approximation of nitrogen using the simple Lennard-Jones potential. In each MD simulation, a liquid film was initialized between vapor regions and NVE-type simulations were run to equilibrium. The simulation domain was divided into bins across the interfacial region for fluid density collection, and the resultant interfacial region density profile was used for surface tension evaluation. Application of the EFEDI method to these MD simulation results exhibited good approximations to surface tension as a function of temperature for both a simple and complex potential.

Usage of graphics processing units for solving molecular dynamics problems

2011 ◽  
Vol 8 (1) ◽  
pp. 182-188
Author(s):  
D.F. Marin
Keyword(s):  
Molecular Dynamics ◽  
Graphics Processing Units ◽  
Computational Scheme ◽  
Lennard Jones Potential ◽  
Jones Potential ◽  
Lennard Jones ◽  
Graphics Processing ◽  
Dynamics Problems

The paper presents results on performance and efficiency of GPU utilization in a simulation of molecular dynamics processes. The simulation was done with the usage of Lennard-Jones potential and leapfrog computational scheme.

Relativistic Molecular Dynamics Simulations of Laser Ablation Process on the Xenon Solid

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Yun-Che Wang ◽  
Jing-Wen Chen ◽  
Lun-De Liao ◽  
Hong-Chang Lin ◽  
Chi-Chuan Hwang
Keyword(s):  
Molecular Dynamics ◽  
Laser Ablation ◽  
Special Relativity ◽  
Coulomb Potential ◽  
Charged Particles ◽  
Lennard Jones Potential ◽  
Ablation Process ◽  
Jones Potential ◽  
Lennard Jones ◽  
Laser Ablation Process

The phenomena of Coulomb explosion require the consideration of special relativity due to the involvement of high energy electrons or ions. It is known that laser ablation processes at high laser intensities may lead to the Coulomb explosion, and their released energy is in the regime of kEV to MeV. In contrast to conventional molecular dynamics (MD) simulations, we adopt the three-dimensional relativistic molecular dynamics (RMD) method to consider the effects of special relativity in the conventional MD simulation for charged particles in strong electromagnetic fields. Furthermore, we develop a Coulomb force scheme, combined with the Lennard-Jones potential, to calculate interactions between charged particles, and adopt a Verlet list scheme to compute the interactions between each particle. The energy transfer from the laser pulses to the solid surface is not directly simulated. Instead, we directly assign ion charges to the surface atoms that are illuminated by the laser. By introducing the Coulomb potential into the Lennard-Jones potential, we are able to mimic the laser energy being dumped into the xenon (Xe) solid, and track the motion of each Xe atom. In other words, the laser intensity is simulated by using the repulsive forces from the Coulomb potential. Both nonrelativistic and relativistic simulations are performed, and the RMD method provides more realistic results, in particular, when high-intensity laser is used. In addition, it is found that the damage depth does not increase with repeated laser ablation when the pulse frequency is comparable to the duration of the pulse. Furthermore, we report the time evolution of energy propagation in space in the laser ablation process. The temporal-spatial distribution of energy indirectly indicates the temperature evolution on the surface of the Xe solid under intense laser illumination.

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