Papers by Keyword: Interatomic Potential

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Authors: Chao Yin, Fei Ye, Chun Yu Yin, Ding Rong Ou, Toshiyuki Mori
Abstract: Six interatomic potentials based on Buckingham potential form for yttria-stablized zirconia have been critically assessed by predicting lattice constants, dielectric constants, and elastic properties using the mean-field approach. The content of Y2O3 is set to the range from 8 to 24 mol%. It has been found out that no potential can reproduce all the fundamental properties. Taking all the simulation and comparison results into consideration, the potential of Butler (1981) displays the highest fidelity, and the potential of Lewis (1985) shows the widest range of applicability.
Authors: X.W. Zhou, D.A. Murdick, B. Gillespie, J.J. Quan, Haydn N.G. Wadley, Ralf Drautz, David Pettifor
Abstract: The atomic-scale structures and properties of thin films are critically determined by the various kinetic processes activated during their atomic assembly. Molecular dynamics simulations of growth allow these kinetic processes to be realistically addressed at a timescale that is difficult to reach using ab initio calculations. The newest approaches have begun to enable the growth simulation to be applied for a wide range of materials. Embedded atom method potentials can be successfully used to simulate the growth of closely packed metal multilayers. Modified charge transfer ionic + embedded atom method potentials are transferable between metallic and ionic materials and have been used to simulate the growth of metal oxides on metals. New analytical bond order potentials are now enabling significantly improved molecular dynamics simulations of semiconductor growth. Selected simulations are used to demonstrate the insights that can be gained about growth processes at surfaces.
Authors: Li Jun Bai, Ping Qian, Yao Wen Hu, Jiu Li Liu
Abstract: The site preference and thermodynamic properties of UTxAl12-x (T = Zr, Nb, Mo and Fe) and their related hydrides are studied based on the pair potentials obtained by the lattice inversion method. The calculated result demonstrates that the stabilizing elements Zr, Nb, or Mo prefer to substitute for Al in 8i sites; and Fe atom preferentially substitutes for Al in the 8f site. The interstitial H atoms only occupy 2b interstitial sites in UTxAl12-x. The calculated lattice parameters coincide with the experimental values. In addition, the total and partial phonon densities of states are first evaluated for these compounds.
Authors: Li Jun Bai, Ping Qian, Yao Wen Hu, Jiu Li Liu
Abstract: An atomistic study is presented on the phase stability, interatomic distances and lattice parameters of the new actinide intermetallic compounds AFe2Al10 (A = Th, U). Calculations are based on a series of interatomic pair potentials related to the actinides and transition metals, which are obtained by lattice inversion method. The cohesive energy of AFe2Al10 with two possible structures of YbFe2Al10-type and ThMn12-type are calculated and compared with each other. Calculated lattice parameters of AFe2Al10 are found to agree with reports in the literatures. In particular, the phonon densities of states, vibrational entropy and Debye temperature related to dynamic phenomena are evaluated for the first time.
Authors: Zhi Bo Zhang, Herbert M. Urbassek
Abstract: We compare the performance of three interatomic interaction potentials for describing the evolution of plasticity and phase transformations in Si: the well established Stillinger-Weber potential, a recent modification used in the description of Al/Si composites, and a modification of the well known Tersoff potential. We show that the generation of dislocations and the evolution of plasticity are well described by the Stillinger-Weber potential and its modification, while the phase transformation to the high-pressure bct5 modification and the subsequent amorphization are better included in the modified Tersoff potential.
Authors: Ryo Kobayashi, Tomoyuki Tamura, Ichiro Takeuchi, Shuji Ogata
Abstract: The validity of the molecular dynamics (MD) simulation is highly dependent on the accuracy or reproducibility of interatomic potentials used in the MD simulation. The neural-network (NN) interatomic potential is one of promising interatomic potentials based on machine-learning method. However, there are some parameters that should be determined heuristically before making the NN potential, such as the shape and number of basis functions. We have developed a new approach to select only relevant basis functions from a lot of candidates systematically and less heuristically without loosing the accuracy of the potential. The present NN potential for Si system shows very good agreements with the results obtained using ab-initio calculations.
Authors: M.I. Pascuet, Julián R. Fernández, A.M. Monti
Abstract: An EAM interatomic potential for the ordered AlMo3 intermetallic is developed and applied to the study of point defects in the AlMo3. The equilibrium concentrations of vacancies and antisites are calculated using statistical thermodynamics. Results show that antisites are the most abundant type of defect in a range of temperatures and compositions close to stoichiometry. Finally, the diffusion by vacancy mechanism in the same structure is studied through the kinetic Monte Carlo technique. Possible atomic mechanisms of diffusion are suggested and analyzed in some detail.
Authors: Han Qing Jiang, Keh Chih Hwang, Young Huang
Abstract: It is commonly believed that continuum mechanics theories may not be applied at the nanoscale due to the discrete nature of atoms. We developed a nanoscale continuum theory based on interatomic potentials for nanostructured materials. The interatomic potential is directly incorporated into the continuum theory through the constitutive models. The nanoscale continuum theory is then applied to study the mechanical deformation and thermal properties of carbon nanotubes, including (1) pre-deformation energy; (2) linear elastic modulus; (3) fracture nucleation; (4) defect nucleation; (5) electrical property change due to mechanical deformation; (6) specific heat; and (7) coefficient of thermal expansion. The nanoscale continuum theory agrees very well with the experiments and atomistic simulations without any parameter fitting, and therefore has the potential to be utilized to complex nanoscale material systems (e.g., nanocomposites) and devices (e.g., nanoelectronics).
Authors: Ibrahim Dauda Muhammad, Mokhtar Awang
Abstract: Molecular modelling methods were used to investigate the structural and interatomic potential of bulk cubic zirconia. To widen the scope of the expected outcome, GULP and CASTEP software were used based on the concept of minimizing the energy of the crystal structure with respect to atomic coordinates. The crystal structure of cubic zirconia was modelled and optimized; the lattice parameter of 5.10 Å obtained is similar to available calculated and experimental values. The developed interatomic potential is based on Born model for ionic solids without defects. The calculated interatomic potential of 109.67eV per atom is also within acceptable range, but variation was observed depending on the relative position of individual atoms. The modelling gave a better understanding of the bulk crystal structure of cubic zirconia due to detailed parameters that were obtained. Also, the determined parameters were used to estimate the Young’s Modulus of bulk zirconia as 397GPa.
Authors: Yoshihiro Kubota, Ryosuke Matsumoto, Michihiko Nakagaki
Abstract: In recent years, nano-crystalline materials have attracted many researchers’ attention, but the fracture mechanism has not been fully clarified. In a molecular dynamics (MD) simulation, grain size and crystal orientation can be chosen, and their effects on the mechanical properties of nano-crystalline materials can be evaluated clearly. This research first compares the results of crack growth behavior in single crystalline Fe for three typical interatomic potentials (Embedded Atom Method (EAM), Finnis Sinclair (FS), and Second Nearest Neighbor Modified EAM (2NNMEAM) potentials) and a Hybrid potential method, which uses FS potential for bcc structure atoms and 2NNMEAM potential for non-bcc structure atoms. The 2NNMEAM potential is accurate, but the computation time is dozens of times that of FS potential, which is the simplest of the three interatomic potentials. Therefore, the 2NNMEAM potential requires too much calculation for the purpose of this research that analyzes the crack growth behavior in nano-crystalline metals. However, Hybrid potential is able to give results similar to those of the 2NNMEAM potential, and the calculation time is close to that of the FS potential. From these results, the crack extension behavior in relatively large nano-crystalline models is analyzed using the Hybrid potential, and we demonstrate the grain-size dependency of the fracture behavior.
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