Lattice dynamical calculations of infinite layer iron oxides SrFeO2 and CaFeO2

TL;DR

This paper presents lattice dynamical calculations for the infinite-layer iron oxides SrFeO2 and CaFeO2, accurately modeling phonon spectra and thermodynamic properties, and demonstrating transferability of potential parameters between the two compounds.

Contribution

It introduces a transferable interatomic potential model for SrFeO2 and CaFeO2, enabling comprehensive phonon and thermodynamic calculations that align with experimental data.

Findings

Phonon spectra calculated across the Brillouin zone agree with experimental data.

Potential parameters are transferable between SrFeO2 and CaFeO2.

Calculated thermodynamic properties match observed structural and thermal behaviors.

Abstract

We report extensive lattice dynamical calculations of the newly discovered infinite-layer iron oxides SrFeO2 and CaFeO2. For SrFeO2, the parameters of the interatomic potential have been determined to reproduce the zone-centre phonon frequencies reported using ab-initio calculations. Further we have extended the potential model for calculations of CaFeO2. The potential parameters are found to be transferable between the two compounds, and are used to calculate the phonon spectra in the whole Brillouin zone and several thermodynamic properties for these compounds. The calculations show fair agreement with the available experimental data of structure, thermal expansion, and mean-squared amplitudes of the atoms.