Papers by Keyword: Lennard-Jones Potential

Abstract: This scientific work presents the development of a computer-simulation model for particle filling in three-dimensional space based on molecular dynamics methods. The Lennard-Jones potential was used to simulate interactions between particles, and the equations of motion were integrated using the Velocity Verlet algorithm. The model incorporates periodic boundary conditions (PBC), ensuring accurate representation of an infinite system without boundary effects. The simulation results confirm the system's energy stability: the total energy remains virtually unchanged throughout the simulation, indicating the correctness of numerical integration. Fluctuations in kinetic and potential energies demonstrate normal system dynamics, where energy is redistributed among particles through interactions. An analysis of the spatial distribution of particles revealed that the system remains in a liquid state, with no signs of solid structure formation or particle aggregation. Notably, the developed model enables the simulation of complex physical processes such as dense structure formation, particle transport, and self-packing. The obtained results highlight the efficiency of the molecular dynamics method for analyzing granular and particulate media, as well as for studying the physical properties of multi-particle systems. The model can be utilized to optimize technological processes related to material transportation, packaging, and storage, as well as for research into nanomaterials and composites.

Abstract: Computer simulation techniques have gained many attentions. The objective of this research was to study influence of the exchangeable cations of Group 1A (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) on the CO₂ adsorption in the system using Grand Canonical Monte Carlo (GCMC) simulation. In this simulation, zeolite is a simulation box. The interaction potential simulation with Lennnard-Jones potential showed that Li⁺ and CO₂ had the greatest molecular attraction with Li⁺ having the highest number of CO₂ molecules in the simulation box. The number of CO_{2 /}molecules in the simulation box are as followed with Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺.

Abstract: In this paper, we adopt boththe Lennard-Jones potential and the mean field theory to determine themolecular interactions between carbon dioxide and the double layered graphenes.In addition, we employ a modified van der Waals equation which takes into accountthe multi-scale effect in the absorption regime todeduce the gravimetric uptakeof carbon dioxide between graphene sheets. We show that the full absorptionoccurs at rather low external pressure at low temperatures while this happensat roughly 0.2bar at room temperature. The current methodology has the merit ofrapid computational times and producing deductive results in comparison to theusual MD simulations.For graphene sheets of a separation of 10 Å, the maximumgravimetric uptake could reach 13.3 wt.%.

Abstract: It is the most effective way to study the effect of global warming on plant morphology by analyzing a plant species on a mount along altitudinal gradients. Altitudinal increase means decrease of temperature and metabolic rate as well. This might affect the leaf morphology greatly. The SEM study reveals that the size of nanopore on the epidermis changes gradually along altitudinal gradients, and the absorbed fine particles on the leaf have almost same size, exhibiting high selectivity over other particles. The study gives a strong proof that morphology change links to global warming.

Abstract: Adsorption of fine particles in air by a leaf is studied experimentally. It is found that each leaf can absorb only a kind of particles with almost same size, and it also exhibits high selectivity over other particles. The SEM study reveals that the size of nanopore on the epidermis is a main factor of the highly selective adsorption; the smaller nanopores can absorb larger nanoparticles in air. The morphology of a lotus leaf, which is waterproof and dustproof, has, on the other hand, many short nanofibrils instead of nanopores. It is concluded that the nanoscale geometrical structure of a surface affects its attraction/repulsion property. The experiment also shows that one square millimeter surface with nanopores in diameter of 18 nm can absorb 2 million nanoparticles of about 200 nm in diameter from air in 24 hours. A better understanding of the adsorption/repulsion mechanism could help the further design of bio-mimetic waterproof/dustproof artificial materials and artificial porous materials/fabrics/nonwovens for adsorption of nanoparticles in air.

Abstract: We investigate the prospect of methane gas storage in carbon nanotubes, and in particular we determine the interaction energy between a methane molecule and (9, 5), (8, 8) and (10,10) carbon nanotubes. Employing the Lennard-Jones potential together with the continuous approximation, we determine analytically the interaction energy for a methane molecule inside a carbon nanotube. Our results indicate that larger tubes are highly favoured sites for methane storage although smaller tubes might be superior for methane adsorption at higher temperatures, especially in the range 400 − 500 K.

Abstract: In this study, we investigate the internal mechanics for a two-state memory device,comprising a charged metallofullerene which is located inside a closed carbon nanotube.Assuming the Lennard-Jones interaction energy and the continuum approximation, the metallofullerenehas two symmetrically placed equal minimum energy positions. On one side theencapsulated metallofullerene represents the zero information state and by applying an externalelectrical field, the metallofullerene can be made to overcome the energy barrier of thenanotube, and pass from one end of the tube to the other, where the metallofullerene thenrepresents the one information state.

Abstract: From the theoretical point of view, characterization of nano particle interaction depends much on the particle diameter , packing factor , the parameter of the Lennard-Jonnes (LJ) pair potential function  (r) and static structure factor S (Q). A novel method suggested in this paper has been tested on seven specific drug delivering fluorocarbons by estimating the strength of interaction /k of  (r) and S(Q) in terms of the elementary parameter . The importance of this paper is that, the input parameter viz., packing factor has been obtained from the experimental ultrasonic velocity of those seven systems. Calculations were extended for different temperatures involving four different equations of states to back up the application of the model. Though there is a lack of analytical results to compare, our predictions are encouraging.

Abstract: Recrystallization is governed by the migration of high angle grain boundaries traveling through a deformed material driven by the excess energy located primarily in dislocation structures. A method for investigating the interaction between a migrating grain boundary and dislocation boundaries using molecular dynamics (MD) was recently developed. During simulations migrating high angle grain boundaries interact with dislocation boundaries, and individual dislocations from the dislocation boundaries are absorbed into the grain boundaries. Results obtained previously, using a simple Lennard-Jones (LJ) potential, showed surprisingly irregular grain boundary migration compared to simulations of grain boundary migration applying other types of driving forces. Inhomogeneous boundary-dislocation interactions were also observed in which the grain boundaries locally acquired significant cusps during dislocation absorption events. The study presented here makes comparisons between simulations performed using a LJ- and an embedded atom method (EAM) aluminum potential. The results show similarities which indicate that it is the crystallographic features rather than the atomic interactions that determine the details of the migration process.

Abstract: We simulate fluid and solid Lennard-Jones argon systems via non-equilibrium molecular dynamics and study how the system behaves under an imposed temperature gradient until it reaches the stationary state, from where the thermal conductivity is calculated. We show that transient pressure waves propagate in the system giving rise to a density oscillation pattern. Based on the damping of this pattern we estimate the time needed to reach the stationary state. We also show that thermal conductivity is size independent in the fluid phase, while it increases until the Casimir limit in the solid phase.