Molecular dynamics simulation of BaMgF₄ and BaMnF₄

Abstract

We have performed molecular dynamics simulations on BaMgF₄ and BaMnF₄, both of which have been reported to have polar structures, with T_c above the melting point. We have determined the ground state structure and verified the polarization mechanism described by Keve et al.¹ Polarizations of 8.5 μC/cm² are found for the Mg compound at 0 K and 11.7 μC/cm² for the Mn compound. We find no indication of ferroelectric phase transitions between 0 K and 1200 K for either material. We are able to reverse the polarization of the Mg compound by simulating a external field, while the Mn based material distorts, but does not reverse polarity. We have simulated substitutions of Be for Mg and Mn in these materials. We report on these results.