1201.6284 (B. Sadigh et al.)

Composition-dependent interatomic potentials: A systematic approach to
modelling multicomponent alloys    [PDF]

B. Sadigh, P. Erhart, A. Stukowski, A. Caro

We propose a simple scheme to construct composition-dependent interatomic
potentials for multicomponent systems that when superposed onto the potentials
for the pure elements can reproduce not only the heat of mixing of the solid
solution in the entire concentration range but also the energetics of a wider
range of configurations including intermetallic phases. We show that an
expansion in cluster interactions provides a way to systematically increase the
accuracy of the model, and that it is straightforward to generalise this
procedure to multicomponent systems. Concentration-dependent interatomic
potentials can be built upon almost any type of potential for the pure elements
including embedded atom method (EAM), modified EAM, bond-order, and
Stillinger-Weber type potentials. In general, composition-dependent N-body
terms in the total energy lead to explicit (N+1)-body forces, which potentially
renders them computationally expensive. We present an algorithm that overcomes
this problem and that can speed up the calculation of the forces for
composition-dependent pair potentials in such a way as to make them
computationally comparable in efficiency and scaling behaviour to standard EAM
potentials. We also discuss the implementation in Monte-Carlo simulations.
Finally, we exemplarily review the composition-dependent EAM model for the
Fe-Cr system [PRL 95, 075702 (2005)].

View original: http://arxiv.org/abs/1201.6284