Weighted multibody expansions for computing stable structures of multiatom systems
Veera Sundararaghavan and Nicholas Zabaras

The effect of structural relaxations in alloys is described using a multi-body energy expansion formalism. $N$-body potentials in the multi-body expansion are computed from energies of isolated clusters, which in turn, are calculated from empirical potentials or self-consistent quantum mechanical calculations. Convergence characteristics of multi-body expansions (MBE) are improved by weighting energies obtained from various truncations of many-body expansion in a new method called weighted MBE (wMBE). It is shown that multi-body expansions of many-atom systems can be efficiently constructed using interpolation of isolated cluster energies from databases. In contrast to the method of cluster expansion, wMBE focuses on positional degrees of freedom and hence, explicitly handles structural relaxations during computations of stable atom clusters and periodic or amorphous phase structures.

© 2008 The American Physical Society.