Fitting to magnetic forces improves the reliability of magnetic Moment Tensor Potentials

• Main Authors: Kotykhov, Alexey S, Gubaev, Konstantin, Sotskov, Vadim, Tantardini, Christian, Hodapp, Max, Shapeev, Alexander V, Novikov, Ivan S
• Format: Journal Article
• Language: English
• Published: 21-08-2024
• Subjects: Physics - Materials Science; Physics - Other Condensed Matter
• DOI: 10.48550/arxiv.2405.07069

We developed a method for fitting machine-learning interatomic potentials
with magnetic degrees of freedom, namely, magnetic Moment Tensor Potentials
(mMTP). The main feature of our method consists in fitting mMTP to magnetic
forces (negative derivatives of energies with respect to magnetic moments) as
obtained spin-polarized density functional theory calculations. We test our
method on the bcc Fe-Al system with different compositions. Specifically, we
calculate formation energies, equilibrium lattice parameter, and total cell
magnetization. Our findings demonstrate an accurate correspondence between the
values calculated with mMTP and those obtained by DFT at zero temperature.
Additionally, using molecular dynamics, we estimate the finite-temperature
lattice parameter and capture the cell expansion as was previously revealed in
experiment. Furthermore, we demonstrate that fitting to magnetic forces
increases the reliability of structure relaxation (or, equilibration), in the
sense of ensuring that every relaxation run ends up with a successfully relaxed
structure (the failure may otherwise be caused by falsely driving a
configuration away from the region covered in the training set).