Introduction

The Alloy-Theoretic Automated Toolkit (ATAT) is a generic name that refers to a collection of alloy theory tools:

• A code to construct cluster expansions from first-principles (MAPS). A cluster expansion is a very compact and efficient expression giving the energy of an substitutional alloy as a function of its configuration (i.e. which type of atom sits where on the lattice).
• A code to perform Monte Carlo simulation of lattice models in order to compute thermodynamic properties of alloys starting from a cluster expansion.
• Extension of the two above tools that allow the construction of so-called reciprocal-space cluster expansion, which are useful to model the energetics of alloys exhibiting a large atomic size mismatch.
• Utilities to interface the above tools with first-principles codes (such as VASP).
• Job control utilities that enable the efficient use of a cluster of workstations to run the first-principles codes that provide the input to the above codes.