Monte Carlo simulations

The emc2 code implements semi-grand canonical Monte Carlo simulations [16,2,8,15], where the total number of atoms is kept fixed, while the concentration is allowed to adapt to an externally imposed difference in the chemical potential of the two types of atoms. The chemical potential difference will be simply referred to as the “chemical potential” in what follows. This ensemble offers the advantage that, for any imposed chemical potential, the equilibrium state of the system is a single phase equilibrium, free of interfaces.^5.3It also simplifies the process of calculating free energies through thermodynamic integration. While a detailed description of the algorithm underlying this code can be found in [22], the current section focuses on the practical usage of the code.