First-principle calculation of the dielectric and dynamical properties of orthorhombic CaMnO$_{3}$

TL;DR

This study uses first-principles density functional theory to analyze the structural, dielectric, and phononic properties of orthorhombic CaMnO₃, revealing large anisotropic dielectric responses and phonon spectra consistent with experimental data.

Contribution

It provides detailed first-principles calculations of the dielectric and dynamical properties of orthorhombic CaMnO₃, including phonon modes and dielectric constants, aligning well with experimental observations.

Findings

Large, anisotropic static dielectric constant observed.

Infrared and Raman phonon modes match experimental data.

Coherent with anomalous Born effective charges and low-frequency polar modes.

Abstract

The structural, dielectric and dynamical properties of the low temperature antiferromagnetic orthorhombic phase of CaMnO$_3$ have been computed from first principles using a density functional theory approach within the local spin density approximation. The theoretical structural parameters are in good agreement with experiment. The full set of infrared and Raman zone-center phonons is reported and compared to experimental data. It is shown that coherently with the anomalous Born effective charges and the presence of low frequency polar modes, the static dielectric constant is very large and highly anisotropic.