Talk on Tuesday at 15:30

Tools for atomic-scale model construction: Cluster expansions and force constants

Mattias Ångqvist,1 Fredrik Eriksson,1 William Armando Muñoz,1 Magnus Rahm,1 Erik Fransson,1 Céline Durniak,2 Piotr Rozyczko,2 Thomas Holm Rod,2 and Paul Erhart1
1Chalmers University of Technology, Sweden
2Data Management and Software Centre, European Spallation Source, Copenhagen Denmark

Slides (pdf)

Modeling the thermodynamic and kinetic properties of materials commonly requires taking into account both vibrational and compositional degrees of freedom. While electronic structure calculations strictly speaking can provide the necessary information, they are computationally too demanding for many practical purposes. One therefore requires models that can reproduce the relevant parts of the potential energy landscape at a much smaller computational cost. Here, we will present a set of software packages that we developed over the course of the last years that allow one to rapidly construct and sample models that map vibrational (hiphive [1]) and/or compositional degrees of freedom (icet [2]). These tools can be integrated in a homogeneous Python based workflow, which combines structure generation, electronic structure calculations, model construction, thermodynamic sampling, and subsequent analysis. Example applications include the prediction of alloy phase diagrams, temperature driven phase transitions, thermal conductivities, and ordering phenomena.

  1. F. Eriksson, E. Fransson, and P. Erhart, Adv. Theory Simul. 1800184 (2019). doi:10.1002/adts.201800184
  2. M. Ångqvist, W. A. Muñoz, J. M. Rahm, E. Fransson, C. Durniak, P. Rozyczko, T. H. Rod, and P. Erhart, Adv. Theory Simul. 1900015 (2019). doi:10.1002/adts.201900015