An automated algorithm for reliable equation of state fitting of magnetic systems

: H.Levämäki, L.-Y. Tian, L.Vitos, M.Ropo

Publisher: ELSEVIER SCIENCE BV

: 2019

: Computational Materials Science

: COMPUTATIONAL MATERIALS SCIENCE

: COMP MATER SCI

: 156

: 121

: 128

: 8

: 0927-0256

DOI: https://doi.org/10.1016/j.commatsci.2018.09.026

In computational physics and materials science ground-state properties are often extracted from an equation of state fit to energy-volume data. Magnetic systems often have multiple magnetic phases present in the energy-volume data, which poses a challenge for the fitting approach because the results are sensitive to the selection of included fitting points. This is because practically all popular equation of state fitting functions, such as Murnaghan and Birch-Murnaghan, assume just one phase and therefore cannot correctly fit magnetic energy-volume data that contains multiple phases. When fitting magnetic energy-volume data it is therefore important to select the range of fitting points in such a way that only points from the one relevant phase are included. We present a simple algorithm that makes the point selection automatically. Selecting fitting points automatically removes human bias and should also be useful for large-scale projects where selecting all fitting points by hand is not feasible.