• Title/Summary/Keyword: molecular dynamics simulation.

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Molecular dynamics study of the elastic moduli of FCC nanofilm (분자동역학을 이용한 FCC 나노박막의 탄성계수 연구)

  • Kim, Won-Bae;Cho, Maeng-Hyo
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1928-1933
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    • 2008

  • In this paper, elastic properties such as Young's modulus and Poisson's ratio of various transition metal nanofilms are calculated for the {100} and {110} surfaces by using molecular dynamics simulation. A new method using $3^{rd}$ order elastic constants and least square method is presented for the calculation of elastic constants. We also introduce analytical method of calculating elastic constants for EAM potential and it's results as the reference value to be compared with the simulation results.

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Molecular Dynamics Simulation of Nano-Deformation Behavior of the Grain-Size Controlled Rheology Material (분자동력학을 이용한 결정립 제어 레오로지 소재의 나노 변형거동 전산모사)

  • Kim J. W.;Youn S. W.;Kang C. G.
    • Transactions of Materials Processing
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    • v.14 no.4 s.76
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    • pp.319-326
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    • 2005

  • In this study, the nano-deformation behavior of semi-solid Al-Si alloy was investigated using a molecular dynamics simulation as a part of the research on the surface crack behavior in thixoformed automobile parts. The microstructure of the grain-size controlled Al-Si alloy consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary phase of the grain-size controlled Al-Si alloy were investigated through the molecular dynamics simulation. The primary phase was assumed to be single crystal aluminum. It was shown that the vacancy occurred at the zone where silicon molecules were.

  • https://doi.org/10.5228/KSPP.2005.14.4.319 인용 PDF KSCI

Estimation of diffusion coefficient at the interface between liquid and vapor phases using the equilibrium molecular dynamics simulation (분자 동역학 모사를 이용한 액상과 기상 계면에서의 확산계수의 예측)

  • Kim, Kyeong-Yun;Choi, Young-Ki;Kwon, Oh-Myoung;Park, Seung-Ho;Lee, Joon-Sik
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1584-1589
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    • 2003

  • This work applies the equilibrium molecular dynamics simulation method to study a Lennard-Jones liquid thin film suspended in the vapor and calculates diffusion coefficients by Green-Kubo equation derived from Einstein relationship. As a preliminary test, the diffusion coefficients of the pure argon fluid are calculated by equilibrium molecular dynamics simulation. It is found that the diffusion coefficients increase with decreasing the density and increasing the temperature. When both argon liquid and vapor phases are present, the effects of the system temperature on the diffusion coefficient are investigated. It can be seen that the diffusion coefficient significantly increases with the temperature of the system.

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The efficiency of subtraction technique in a nonequilibrium molecular dynamics simulation of a simple liquid shear flow (단순액체의 층밀리기 흐름에 대한 비평형 분자동력학 계산에서 공제방법의 효과)

  • 안성청
    • Journal of the Korea Society for Simulation
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    • v.6 no.1
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    • pp.53-60
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    • 1997

  • Results from a nonequilibrium molecular dynamics (NEMD) simulation are presented for an argon liquid subject to a shear flow. The segmented molecular dynamics method and the subtraction technique used in NEMD program to reduce the thermal fluctuation noise in data are studied with different shear rates. The standard deviation in the shear stress reduced from 0.030 to 0.004 by the segmented molecular dynamics method for 50 repeated segments. On the other hand, the standard deviation of the data remained the same when the subtraction technique was applied, where as the results of shear stress by constant value in a random way.

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Hydrogen Bonds in GlcNAc( β1,3)Gal( β)OMe in DMSO Studied by NMR Spectroscopy and Molecular Dynamics Simulations

  • Shim, Gyu-Chang;Shin, Jae-Min;Kim, Yang-Mee
    • Bulletin of the Korean Chemical Society
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    • v.25 no.2
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    • pp.198-202
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    • 2004

  • Hydrogen bond is an important factor in the structures of carbohydrates. Because of great strength, short range, and strong angular dependence, hydrogen bonding is an important factor stabilizing the structure of carbohydrate. In this study, conformational properties and the hydrogen bonds in GlcNAc( ${\beta}$1,3)Gal(${\beta}$)OMe in DMSO are investigated through NMR spectroscopy and molecular dynamics simulation. Lowest energy structure in the adiabatic energy map was utilized as an initial structure for the molecular dynamics simulations in DMSO. NOEs, temperature coefficients, SIMPLE NMR data, and molecular dynamics simulations proved that there is a strong intramolecular hydrogen bond between O7' and HO3' in GlcNAc( ${\beta}$1,3)Gal(${\beta}$)OMe in DMSO. In aqueous solution, water molecule makes intermolecular hydrogen bonds with the disaccharides and there was no intramolecular hydrogen bonds in water. Since DMSO molecule is too big to be inserted deep into GlcNAc(${\beta}$1,3)Gal(${\beta}$)OMe, DMSO can not make strong intermolecular hydrogen bonding with carbohydrate and increases the ability of O7' in GlcNAc(${\beta}$1,3)Gal(${\beta}$)OMe to participate in intramolecular hydrogen bonding. Molecular dynamics simulation in conjunction with NMR experiments proves to be efficient way to investigate the intramolecular hydrogen bonding existed in carbohydrate.

  • https://doi.org/10.5012/bkcs.2004.25.2.198 인용 PDF KSCI