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Delocalized nonlinear vibrational modes in fcc metals
Communications in Nonlinear Science and Numerical Simulation ( IF 3.4 ) Pub Date : 2021-09-08 , DOI: 10.1016/j.cnsns.2021.106039
S.A. Shcherbinin 1, 2 , K.A. Krylova 3, 4 , G.M. Chechin 2 , E.G. Soboleva 5 , S.V. Dmitriev 3, 6
Affiliation  

Nonlinear lattices support delocalized nonlinear vibrational modes (DNVMs) that are exact solutions to the dynamical equations of motion dictated by the lattice symmetry. Since only lattice symmetry is taken into consideration for derivation of DNVMs, they exist regardless the type of interaction between lattice points, and for arbitrary large amplitude. Here, considering space symmetry group of the fcc lattice, we derive all one-component DNVMs, whose dynamics can be described by single equation of motion. Twelve such modes are found and their dynamics are analyzed for Cu, Ni, and Al based on ab initio and molecular dynamics simulations with the use of two different interatomic potentials. Time evolution of atomic displacements, kinetic and potential energy of atoms, and stress components are reported. Frequency–amplitude dependencies of DNVMs obtained in ab initio simulations are used to assess the accuracy of the interatomic potentials. Considered interatomic potentials (by Mendelev et al. and Zhou et al.) for Al are not as accurate as for Cu and Ni. Potentials by Mendelev can be used for relatively small vibration amplitudes, not exceeding 0.1 Å, while potentials by Zhou are valid for larger amplitudes. Overall, the presented family of exact solutions of the equations of atomic motion can be used to estimate the accuracy of the interatomic potentials of fcc metals at large displacements of atoms.



中文翻译:

fcc金属中的离域非线性振动模式

非线性晶格支持离域非线性振动模式 (DNVM),它是由晶格对称性决定的运动动力学方程的精确解。由于在推导 DNVM 时仅考虑晶格对称性,因此无论晶格点之间的相互作用类型如何,对于任意大振幅,它们都存在。在这里,考虑 fcc 晶格的空间对称群,我们推导出所有单分量 DNVM,其动力学可以用单个运动方程来描述。发现了 12 种这样的模式,并基于从头算分析了它们对 Cu、Ni 和 Al 的动力学使用两种不同的原子间势进行分子动力学模拟。报告了原子位移、原子的动能和势能以及应力分量的时间演变。在ab initio模拟中获得的 DNVM 的频率-幅度相关性用于评估原子间势的准确性。考虑原子间势(由 Mendelev人和 Zhou等人提出。) 对于 Al 不如 Cu 和 Ni 准确。Mendelev 的电位可用于相对较小的振幅,不超过 0.1 Å,而 Zhou 的电位适用于较大的振幅。总体而言,所提出的原子运动方程的精确解族可用于估计原子大位移时 fcc 金属的原子间势的准确性。

更新日期:2021-09-27
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