An alternative methodology to assess the quality of empirical potentials for small gold clusters

•We assess the quality of five typical empirical potentials.•This study is carried out on small neutral gold clusters.•The methodology is based on local comparisons of potential energy surfaces (PES).•A many-body expansion of the PES in terms of normal coordinates is performed.•1D and 2D indices are defined in order to assign a magnitude to the variations of the PES.

We present a methodology based on local comparisons of potential energy surfaces (PES) in order to assess the quality of empirical potentials. We compare five typical empirical potentials using a criterion that shows which of these potentials resembles better a PES obtained with a high-level electronic structure method. The methodology relies on a many-body expansion in terms of normal coordinates of both the empirical and high-level theory PES. Then we investigate in a systematical way, how the features of the reference high-level theory PES are reproduced by each empirical potential in the vicinity of a given minimum energy structure. We use plane-wave density functional theory (DFT) as a reference, in particular the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional and an ultrasoft Vanderbilt pseudo potential. This study is carried out on neutral gold clusters with up to five atoms.

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