Papers by Keyword: Molecular Dynamic Simulation

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Authors: Ming Liang Liao, Ting Wei Lian, Shin Pon Ju
Abstract: Temperature effects on tensile and compressive behaviours of an (8,8) boron nitride nanotube (BNNT) were investigated via the molecular dynamics (MD) simulations with the Tersoff potential parameters determined by fitting the MD simulations results to those obtained from the density functional theory calculations. The force-matching method was employed in the fitting process. It was noticed that the failure strain of the BNNT decreases from 33.9% at temperature of 50 K to 26.7% at temperature of 300 K and the critical buckling strain degrades from 5.46% to 3.98%. No obvious yielding occurs before the tensile failure of the BNNTs. A chain-like tensile failure mode was observed prior to complete breaking of the BNNT. In addition, when the BNNT was loaded beyond the critical buckling strain it behaves in a symmetrical buckling mode with a flat cross section near the middle of the BNNT.
Authors: Zhang Yang, Chen Wen Bo, Bai Qi Feng, Lian Li
Abstract: GPU computing is the use of a graphics processing unit together with a CPU to accelerate large scale scientific and engineering applications, such as molecule simulation. The paper use NVIDIA Tesla C2050NVIDIA GTX580 and NAMD 2.9 simulates three differences molecule systems: Beta2,SET9 and Ubiquitin. We compared and analyzed the results of the simulations experiment, and come to conclusion that the difference molecule systems will get the difference speed accelerated. The computing times of four GPU is nearly half of the time used by one GPU; and this is especially in the case of macromolecules system. Furthermore, from the GPUs memory utilization rate, the larger the protein system is, the higher the memory use of the GPU is. The performance of NVIDIA GTX580 is only half of the NVIDIAC2050. NVIDIA Tesla C2050 is can satisfy an even larger system simulation.
Authors: J. Davoodi, M. Ahmadi
Abstract: In this investigation, we focused on the effects of pressure on the melting of elements Cu, Pd as well as Pd3Cu order alloy. We have performed molecular dynamics based computations of the variation of the physical properties of the elements Cu, Pd and Pd3Cu alloy with pressure and temperature. The quantum Sutton-Chen many-body interatomic potentials have been used for these elements, and the standard mixing rule has been used to obtain the parameters of this potential for the alloy state. This molecular dynamics simulation was performed in the NPT ensemble. Our study enabled us to predict the thermodynamic properties such as melting temperature, isobaric heat capacity as well as the lattice thermal expansion. The temperature dependence of energy and density were calculated at high pressure. Moreover, we presented the variation of the melting temperature, heat capacity as well as the thermal expansion of the crystal with pressure. The obtained results showed that the melting temperature increase with increasing pressure and isobaric heat capacity as well as lattice thermal expansion decrease with increasing pressure. Our computed results are in reasonable agreement with the experimental data where they are available.
Authors: Xiao Jing Gong, Jing Ping Zhang, Ke Xu, Zhi Gao Wang, Hui Yang, Rong Yu, Wei Zhan
Abstract: Semiconducting nanowires offer the possibility of nearly unlimited complex bottom-up design, which allows for new device concepts. However, essential parameters that determine the electronic quality of the wires, and which have not been controlled yet for the III–V compound semiconductors, are the wire crystal structure and the stacking fault density. In this paper, we have used the molecular dynamics simulations to study the formation of the stacking faults in GaN NW along [0001] and [11-20] directions. The results show that under same growth condition the GaN NW along [0001] has stacking fault while there is no stacking fault in GaN NW along [11-20]. We have analysis the possible reason and further study is underway.
Authors: Jeffrey Yue, Xu Chuan Jiang, Ai Bing Yu
Abstract: Goethite (α-FeOOH) nanorods could be prepared by a surfactant directed approach in aqueous solution at ambient conditions. In this approach, it is observed that the surfactants (e.g, cetyltrimethylammonium bromide (CTAB) and tetraethylamine chloride (TEAC)) play a key role in the growth of goethite nanorods under the reported conditions. The molecular dynamics (MD) method is used to understand the underlying principle governing particle formation and growth through the analysis of the interaction energies between the crystal surfaces and the surfactant molecules. The findings will be useful for understanding the growth mechanism of anisotropic particles and their surface coatings with heterogeneous materials for desired functional properties.
Authors: Xing Li Zhang, Zhao Wei Sun
Abstract: Molecular, dynamics simulation and the Boltzmann transport equation are used respectively to analyze the phonon transport in Si thin film. The MD result is in good agreement with the theoretical analysis values. The results show that the calculated thermal conductivity decreases almost linearly as the film thickness reduced and is almost independent of the temperature at the nanoscale. It was observed from the simulation results that there exists the obvious size effect on the thermal conductivity.
Authors: Ya Dong Liu, Ke Dong Bi, Yun Fei Chen, Min Hua Chen
Abstract: Nonequilibrium molecular dynamics (NEMD) approach is developed to investigate the thermal transport across a solid-solid interface between two different materials with an interlayer around it. The effects of system size and the interlayer material’s properties on the interface thermal resistance are considered in our model. The NEMD simulations show that the addition of an interlayer between two highly dissimilar lattices depresses the interface thermal resistance effectively. Meanwhile, the effective thermal conductivity along the direction of heat flux is enhanced with the increasing system temperature. Moreover, the interface thermal resistance after including an interlayer does not depend strongly on the simulation system size.
Authors: Jin Ray Hsu, Chih Chung Hsiao, Cheng Kuo Sung, Chaug Liang Hsu
Abstract: Molecular dynamics (MD) simulation and the experiment of adhesion force measurement were introduced to study the nanostructure formation process in the atomic force microscopy. The atomic level process of the nanostructure formation and the thermo-mechanical effect caused by the factors of the contact area, the adhesion force, and the temperature were clearly shown and discussed. The size of the forming nanostructures was found to be positively related to the contact area and temperature, but the adhesion force would decrease as the temperature increase. In the case of higher temperature with smaller adhesion force, however, the larger-size nanostructure could still be made.
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