Papers by Keyword: Interatomic Potential

Abstract: Interatomic potential plays an important role in molecular dynamics simulation, which determines both the efficiency and accuracy of the simulations. Lattice inversion is a method which can be used to develop interatomic potential from first principle results directly. In present work, a robust potential model based on lattice inversion is proposed. Then the potential model is applied to develop interatomic potentials for eight common FCC metals. The cohesive energy curves calculated using first principle calculations can be well reproduced, which verifies the reliability of the developed potential. Additional physical properties, including equilibrium lattice constant and cohesive energy, elastic constants, are predicted and found reasonable agreement with corresponding first principle results.

Abstract: Self-irradiation effect induced by Pu α decay is an important influencing factor for long-term storage of Pu-based materials. In order to reveal the collision displacement cascade for uranium recoil nucleus induced by alpha decay in delta-phase plutonium at atomic level, we review the recent progress in self-irradiation of metallic plutonium and its alloys. We perform a molecular dynamics (MD) calculation on basis of modified embedded atom (MEAM) interatomic potentials, and obtain the minimum of displacement threshold energy (MDTE) for {1 1 1} lattice direction and microscopic evolution of He self-interstitial cluster. These findings are in agreement with previous experimental and theoretical results, and can be viewed as an essential input parameter for mesoscopic simulation to obtain the evolution of microscopic configuration at longer time and space, and might be also helpful for understanding the nucleation and growth mechanisms for vacancy and/or self-interstitial and its clusters, He-vacancy cluster and He bubbles in delta-phase plutonium and its alloys.

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.

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.

Abstract: For materials, science it is important to study the structure and behavior of matter at the deepest level. Currently, modern microscopes allow one to see the atomic structure of matter. Materials should be prepared in a special way, for research in the microscope, but thus the natural structure of the material may changed. Especially, the processes at the atomic level are difficult to explore. In a computer model of matter, one can account the properties of atoms and even its electron structure. In this paper, by molecular dynamics method the structure and evolution of the palladium and its compounds with hydrogen are investigated. In the work equilibrium structure of the crystal lattice of palladium was obtained and determined the equilibrium lattice parameter at different temperatures. The behavior of the hydrogen atom inside the crystal lattice of palladium was studied. The structural and diffusion properties system palladium-hydrogen were obtained

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.

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.

Abstract: The Finnis-Sinclair many-body potential was fitted for binary FeAl alloy with B2 structure. As the examination to the acquired potential function, some properties were calculated, and the results agree with the experiments well. Further, properties of point defects, such as divacancies were studied as an application.

Abstract: The phase stability, crystal structure and mechanical properties of YT₂Zn₂₀ and SmT₂Zn₂₀ (T=Fe, Ru, Os, Co, Rh and Ir) compounds have been investigated by using interatomic potentials based on the lattice inversion technique. The calculated lattice constants are in good agreement with the experimental data. The lattice constants increase and Bulk modulus decrease as the transition metal T varies from 3d to 5d. The Y-based compounds with lower energies are more stable than the Sm analogs. Also, the Bulk modulus of YT₂Zn₂₀ series are larger than SmT₂Zn₂₀ series. Moreover, the mechanical properties of the quaternary compounds YFe_2-xCo_xZn₂₀ and SmFe_2-xCo_xZn_20­, such as the elastic constants and bulk modulus, have been calculated in this work_. The substitution of Co atoms would decrease the cohesive energies and increase the bulk modulus of materials.

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.