Computational thermodynamics from the bottom up

A. Presenting Author, A. Second Author Department of Materials,

Imperial College , Exhibition Road, London SW7 2AZ, UK A. Third. Author

Department of Materials and Department of Physics,Thomas Young Centre, Imperial College London,

Exhibition Road, London SW7 2AZ, UK

This is a rambling abstract of a talk that I won’t be giving. There is much interest in acquiring data on the free energy of materials by atomistic simulation, including methods of total energy calculation such as density functional theory. This is usually because the corresponding experimental data would be difficult or impossible to obtain. One might want such data for predicting the stability of complex phases, the free energies of solid-solid interfaces, the diffusion and segregation behaviour in ceramics, metals and semiconductors, and the modelling of solid-liquid interfaces. We review some current methods, achievements and problems. We have attempted to reconcile the very different approaches to calculating the thermodynamic consequences of point defects as practised by the Calphad and atomistic simulation communities [1]. Our work recently has applied quasiharmonic and anharmonic lattice dynamics and methods of biased molecular dynamics and Monte Carlo simulation (E.g. Metadynamics and Wang-Landau Monte Carlo). Applications include i) specific heats and thermal expansion of carbides and borides of Zr and Hf, ii) modelling the effect of high concentrations of point defects on free energy [2], iii) the excess free energy of crystal-melt interfaces in Al.

References[1] Rogal, J.; Divinski, S. V.; Finnis, M. W.; Glensk, A.; Neugebauer, J.;

Perepezko, J. H.; Schuwalow, S.; Sluiter, M. H. F.; Sundman, B., Perspectives on point defect thermodynamics. Physica Status Solidi B 2014, 251, 97-129.

[2] Horton, R. M.; Haslam, A. J.; Galindo, A.; Jackson, G.; Finnis, M. W., New Methods for Calculating the Free Energy of Charged Defects in Solid Electrolytes. J. Phys: Condens. Matter 2013, 25, 395001-1-9.

[3] Another reference