Publications

Automated free-energy calculation from atomistic simulations

S. Menon, Y. Lysogorskiy, J. Rogal, R. Drautz.

Physical Review Materials, American Physical Society,, 5, 103801, (2021)

The pressure-temperature phase diagram for Ti using an embedded atom method (EAM) potential. The regions of stability for bcc, hcp, and liquid are shown in red, green, and blue, respectively. The gradients in the color indicate decreasing free energy; darker color indicates decreasing free energy. Coexistence lines calculated using Algorithm 3 are shown in gray. The coexistence line is further verified by using Algorithm 1, the results of which are shown as gray circles. The three independent computations are in excellent agreement.

Abstract
We devise automated workflows for the calculation of Helmholtz and Gibbs free energies and their temperature and pressure dependence and provide the corresponding computational tools. We employ nonequilibrium thermodynamics for evaluating the free energy of solid and liquid phases at a given temperature and reversible scaling for computing free energies over a wide range of temperatures, including the direct integration of P−T coexistence lines. By changing the chemistry and the interatomic potential, alchemical and upscaling free energy calculations are possible. Several examples illustrate the accuracy and efficiency of our implementation.

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