• 대한금속재료학회지
• /
• 제47권1호
• /
• pp.32-37
• /
• 2009

Molecular dynamic simulations on the structural evolution of the Si(001) vicinal surfaces, which are tilted with respect to [100] and [110] directions were performed by using the empirical Tersoff potential. Tersoff potential was implemented at LAMMPS code and confirmed to describe the properties of Si. When the steps are generated along [100] direction, symmetric dimer rows formed with respect to the step edges. On the other hand, when the steps are generated along [110] direction, alternating dimer rows form with respect to the step edges. The configurational differences between the two vicinal surfaces were discussed in terms of the surface diffusion and the possibility of preventing step bunching for the (001) vicinal surface tilted along [100] direction was suggested.

• 한국전기전자재료학회논문지
• /
• 제17권2호
• /
• pp.127-137
• /
• 2004

We have investigated the structures, the energetic, and the nanomechanics of the single-wall boron-, aluminum-, and gallium-nitride nanotubes using atomistic simulations based on the Tersoff-type potential. The Tersoff-type potential for the III-nitride materials has effectively described the properties of the III-nitride nanotubes. Nanomechanics of boron-, aluminum-, and gallium-nitride nanotubes under the compression loading has been investigated and their Young's moduli were calculated.

• 한국결정학회지
• /
• 제2권1호
• /
• pp.27-31
• /
• 1991

반경험적인 Tersoff 포텐셜을 사용한 lattice statics 시뮬레이션 테크닉에 의하여 C24와 C60 fullerenes의 구조와 에너지를 구하였다. 그 결과는 ab initio 계산 결과와 잘 일치 하였다.

• 한국진공학회지
• /
• 제12권4호
• /
• pp.281-287
• /
• 2003

본 연구에서는 분자동력학 방법을 사용하여 탄소 나노튜브와 같은 구조적 특성을 가정한 실리콘 나노튜브에 관한 연구를 수행하였다. 흑연판 모양의 실리콘 판에서 실리콘 나노튜브가 형성되는 활성화에너지는 매우 낮다는 것을 실리콘판 - 튜브 전이 에너지 도식도를 통하여 살펴보았다. 분자동력학 시뮬레이션 결과는 실리콘의 경우 단일벽 나노튜브가 불안정하며, 다중벽 나노튜브의 경우에 더욱 안정하다는 것을 원자결합수 및 결합각도 분포 비교를 통하여 보여주었다.

• Interaction and multiscale mechanics
• /
• 제4권4호
• /
• pp.247-255
• /
• 2011

Understanding the structural stability of carbon nanostructure under heat treatment is critical for tailoring the thermal properties of carbon-based material at small length scales. We investigate the heat resistance of the single carbon nanoball ($C_{60}$) and carbon nanoonions ($C_{20}@C_{80}$, $C_{20}@C_{80}@C_{180}$, $C_{20}@C_{80}@C_{180}C_{320}$) by performing molecular dynamics simulations. An empirical many-body potential function, Tersoff potential, for carbon is employed to calculate the interaction force among carbon atoms. Simulation results shows that carbon nanoonions are less resistive against heat treatment than single carbon nanoballs. Single carbon nanoballs such $C_{60}$ can resist heat treatment up to 5600 K, however, carbon nanoonions break down after 5100 K. This intriguing result offers insights into understanding the thermal-mechanical coupling phenomena of nanodevices and the complex process of fullerenes' formation.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 추계학술대회논문집
• /
• pp.339-346
• /
• 2003

Molecular dynamic simulations of nano indentation on single-crystal silicon (100) surface were performed using diamond indentor. Silicon substrate and diamond indentor were modeled diamond structure with Tersoff potential model. Phase transformation of silicon, incipient plastic deformation, change of incident temperature distribution are investigated through the change of potential energy distribution, displacement-load diagram, the change of kinetic energy distribution and displacements of silicon atoms. Phase transformation is highly localized and consists of a high-density region surrounding the tip. Axial load linearly increased according to the indenting depth. Number of atoms with high kinetic energy increased at the interface between substrate and indentor tip.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2007년도 추계학술대회 논문집
• /
• pp.348-351
• /
• 2007

Simulations of the buckling behavior of a single wall carbon nanotube(SWCNT) was carried out using molecular dynamics simulation. Molecular dynamics simulations were done with 1fs of time step. Tersoff's potential function was used as the interatomic potential function since it has been proved to be reliable to describe the C-C bonds in carbon nanotubes. Compressive force was applied by moving the top end of the nanotube at a constant velocity. Buckling behavior under compressive load was observed for (15,15) armchair SWCNTs with 2nm of diameter and 24.9nm of length. Buckling load and critical strain is obtained from the MD simulation. Deformation occurred on the top region of the CNT because of fast downward velocity.

• 대한금속재료학회지
• /
• 제49권6호
• /
• pp.425-439
• /
• 2011

A review of the development history of interatomic potential models for ionic materials was carried out paying attention to the way of future development of an interatomic potential model that can cover ionic, covalent and metallic bonding materials simultaneously. Earlier pair potential models based on fixed point charges with and without considering the electronic polarization effect were found to satisfactorily describe the fundamental physical properties of crystalline oxides (Ti oxides, $SiO_2$, for example) and their polymorphs, However, pair potential models are limited in dealing with pure elements such as Ti or Si. Another limitation of the fixed point charge model is that it cannot describe the charge variation on individual atoms depending on the local atomic environment. Those limitations lead to the development of many-body potential models(EAM or Tersoff), a charge equilibration (Qeq) model, and a combination of a many-body potential model and the Qeq model. EAM+Qeq can be applied to metal oxides, while Tersoff+Qeq can be applied to Si oxides. As a means to describe reactions between Si oxides and metallic elements, the combination of 2NN MEAM that can describe both covalent and metallic elements and the Qeq model is proposed.

• Interaction and multiscale mechanics
• /
• 제1권2호
• /
• pp.303-315
• /
• 2008

In this paper, thermodynamical properties of crystalline silicon under strain are calculated using classical molecular dynamics (MD) simulations based on the Tersoff interatomic potential. The Helmholtz free energy of the silicon crystal under strain is calculated by using the ensemble method developed by Frenkel and Ladd (1984). To account for quantum corrections under strain in the classical MD simulations, we propose an approach where the quantum corrections to the internal energy and the Helmholtz free energy are obtained by using the corresponding energy deviation between the classical and quantum harmonic oscillators. We calculate the variation of thermodynamic properties with temperature and strain and compare them with results obtained by using the quasi-harmonic model in the reciprocal space.

• International Journal of Safety
• /
• 제5권1호
• /
• pp.10-16
• /
• 2006

A suspended hemispherical silicon asperity moving over a silicon plate was simulated. The simulation results on friction and wear in the interface between the two can help obtain more durable miscroscale structures. Silicon structures were constructed with Tersoff three-body potential. Dependence of friction and wear of the asperity on both the atomic arrangement in the plate and the moving direction was investigated under the condition that the asperity is subject to the attractive normal force due to the plate. The results show that the variation of friction force with the movement of asperity, and the occurrence of adhesive wear are attributed to the formation and rupture of asperity, junction between the asperity and the plate. The friction force and wear are smaller when the asperity is incommensurate with the plate, and they also depend on the moving direction of the asperity over the plate.