Combining a reactive potential with a harmonic approximation for molecular dynamics simulation of failure: construction of a reduced potential

3rd International Conference on Mathematical Modeling in Physical Sciences

物理学;数学

Tejada, I.G.^1 ; Brochard, L.^1 ; Stoltz, G.^2,3 ; Legoll, F.^1,3 ; Lelièvre, T.^2,3 ; Cancès, E.^2,3

Université Paris-Est. Laboratoire Navier (UMR 8205), CNRS, IFSTTAR, 6 and 8 avenue Blaise Pascal, Marne-la-Vallée

77455, France^1

Université Paris-Est. CERMICS, École des Ponts ParisTech (ENPC), 6 and 8 avenue Blaise Pascal, Marne-la-Vallée

77455, France^2

INRIA Rocquencourt, MATHERIALS Research-team, Le Chesnay Cedex

78153, France^3

关键词: Experimental values;    Harmonic approximation;    Interatomic potential;    Molecular dynamics simulations;    Reactive empirical bond order potential;    Second-order approximation;    Simulation technique;    Two-dimensional materials;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/574/1/012041/pdf
DOI  :  10.1088/1742-6596/574/1/012041

来源: IOP

【 摘 要 】

Molecular dynamics is a simulation technique that can be used to study failure in solids, provided the inter-atomic potential energy is able to account for the complex mechanisms at failure. Reactive potentials fitted on ab initio results or on experimental values have the ability to adapt to any complex atomic arrangement and, therefore, are suited to simulate failure. But the complexity of these potentials, together with the size of the systems considered, make simulations computationally expensive. In order to improve the efficiency of numerical simulations, simpler harmonic potentials can be used instead of complex reactive potentials in the regions where the system is close to its ground state and a harmonic approximation reasonably fits the actual reactive potential. However the validity and precision of such an approach has not been investigated in detail yet. We present here a methodology for constructing a reduced potential and combining it with the reactive one. We also report some important features of crack propagation that may be affected by the coupling of reactive and reduced potentials. As an illustrative case, we model a crystalline two-dimensional material (graphene) with a reactive empirical bond-order potential (REBO) or with harmonic potentials made of bond and angle springs that are designed to reproduce the second order approximation of REBO in the ground state. We analyze the consistency of this approximation by comparing the mechanical behavior and the phonon spectra of systems modeled with these potentials. These tests reveal when the anharmonicity effects appear. As anharmonic effects originate from strain, stress or temperature, the latter quantities are the basis for establishing coupling criteria for on the fly substitution in large simulations.