Delocalized nonlinear vibrational modes in Ni3Al

• Published in: Communications in nonlinear science & numerical simulation 2024-05, Vol.132, Article 107890
• Main Authors: Bachurina, O.V., Murzaev, R.T., Shcherbinin, S.A., Kudreyko, A.A., Dmitriev, S.V., Bachurin, D.V.
• Format: Article
• Language: English
• Subjects: Binary Ni3Al alloy; Delocalized nonlinear vibrational modes; L12 structure; Molecular dynamics simulations; Nonlinear dynamics
• ISSN: 1007-5704; 1878-7274
• DOI: 10.1016/j.cnsns.2024.107890

Delocalized nonlinear vibrational modes (DNVMs) in crystals are exact solutions to the equations of atomic motion. They are determined solely by the symmetry of the lattice, and therefore exist for any interatomic potential and amplitude. DNVMs have been extensively studied in monoatomic crystals. In this work, they are analyzed for the first time in a binary Ni3Al alloy. A class of DNVMs in which only the cubic aluminum sublattice oscillates while the nickel atoms are at rest is considered. Using molecular dynamics, sixteen such DNVMs were found to be able to maintain time-periodic oscillations. The frequency response of the DNVMs was calculated in the wide range of oscillation amplitudes, using three different interatomic potentials. Most of the DNVMs exhibit a hard type nonlinearity when the frequency increases with increasing amplitude. The total energy and the ratio of the total to kinetic energy averaged over the oscillation period (related to the heat capacity of the crystal) were calculated as functions of amplitude. The difference between the results obtained with different potentials suggests the use of DNVMs to check the accuracy of interatomic potentials for binary alloys with L12 structure by comparing the frequency responses obtained from ab initio simulations with similar data from molecular dynamics simulations. •Twenty-five three-dimensional DNVMs in a binary alloy Ni3Al are analyzed.•Excitation of DNVMs on the Al sublattice does not excite the Ni sublattice.•Amplitude–frequency characteristics depend on the interatomic potential used.•The differences in results are partly explained by the Al–Al part of the potentials.•Excitation of DNVMs changes the ratio of total to kinetic energy.