An approach to evaluate the accuracy of interatomic potentials as applied to tungsten

Molecular dynamics (MD) is a powerful tool for modeling structural transformations in metallic materials under irradiation, severe plastic deformation, laser processing, etc. The accuracy of MD modeling is directly related to the quality of the interatomic potentials used. The number of interatomic potentials available is growing very rapidly, and there is a great need to develop a unified approach to evaluate their accuracy, and one such approach is proposed in this work. The theoretical basis of the approach is the use of exact solutions of the equations of motion for the considered lattice. Such solutions, called delocalized nonlinear vibrational modes (DNVMs), are determined solely on the basis of lattice symmetry and for this reason they exist for any interatomic potential and for arbitrarily large amplitudes. The DNVM properties can be calculated using an ab initio approach to obtain data to verify the accuracy of the MD potentials. Analysis of DNVMs is a fundamentally new approach to checking the quality of interatomic potentials, which analyzes not the configurations of atoms, but the trajectories of their motion. Here, this approach is applied to bcc tungsten to evaluate the quality of nine commonly used interatomic potentials. The proposed method can be used as an effective testing tool to supplement existing methods for testing interatomic potentials.