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.