Generalized Universal Equation of States for Magnetic Materials. Part I: A Formulation for Interatomic Potentials

Generalized Universal Equation of States for Magnetic Materials. Part I: A Formulation for Interatomic Potentials

Generalized Universal Equation of States for Magnetic Materials. Part I: A Formulation for Interatomic Potentials 150 150 Mathew
UKAEA-CCFE-PR(22)20

Generalized Universal Equation of States for Magnetic Materials. Part I: A Formulation for Interatomic Potentials

In this work, the Universal Equation of States (UES) is revisited and generalised by including ferromagnetic and antiferromagnetic configurations. The energy of a system is calculated by means of three parameters, namely, the energy, volume and corresponding scaling volume (directly related to the bulk modulus) at the local ground state of the corresponding lattice. These parameters depend on two distance-dependent functions and two magnetic-dependent functions. The first distance dependent function is magnetic-independent, and gathers the non-magnetic influence of the surrounding atoms, while the first magnetic-dependent function is distance-independent, and contributes to the energy by means of the magnetic nature of the atom, irrespective of the magnetic moment magnitudes of its surrounding atoms. Finally, the other distance and magnetic dependent functions are interlinked and collects the influence of the magnetic state of the surrounding atoms into the energy considering their interatomic distance. The new formulation is tested for magnetic iron, where 18240 spin polarized DFT calculated energies for different lattices, volumes and magnetic moments in ferromagnetic and antiferromagnetic configurations showed that the GUES (Generalized Universal Equation of States) describes accurately the energy of the system. The root-mean-square error (RMSE) of the GUES is in the range of 5.9 ·10-3 eV over all DFT calculated energies showing an outstanding accuracy and allows proposing formulations for developing magnetic interatomic potentials. (The figures shown in this article can be seen in colour only in the electronic version)

Collection:
Journals
Journal:
Physical Review Materials
Publisher:
APS (American Physical Society)
Published date:
28/04/2022
The published version of this paper is currently under embargo and will be available on 28/04/2023