Lattice Parameters and Bulk Modulus of SrTi$_{1-\mathit{x}}$Mn$_{\mathit{x}}$O$_{3}$ Perovskites: A Comparison of Exchange-Correlation Functionals with Experimental Validation

TL;DR

This study evaluates four exchange-correlation functionals in predicting lattice parameters and bulk moduli of SrTi$_{1-x}$Mn$_{x}$O$_{3}$ perovskites, validating predictions with experimental data and identifying the most accurate functionals.

Contribution

It compares the accuracy of different functionals in predicting structural properties of SrTi$_{1-x}$Mn$_{x}$O$_{3}$ and validates them against experimental measurements.

Findings

PBEsol and WC functionals provide the most accurate lattice parameters.

Predicted bulk moduli increase linearly with Mn content.

PBEsol and WC closely match experimental bulk modulus of SrTiO$_{3}$.

Abstract

We assessed four exchange-correlation functionals (LDA CA-PZ, GGA parametrized by PBE, PBEsol, and WC) in predicting the lattice parameters of SrTi$_{1-\mathit{x}}$Mn$_{\mathit{x}}$O$_{3}$ perovskites, assuming cubic structures. Predictions were verified using X-ray diffraction (XRD) for Mn content of $\mathit{x}$ = 0.0, 0.1, 0.2, 0.3, 0.5, 1.0, confirming cubic symmetry and a linear decrease in lattice parameters with increasing Mn. PBEsol and WC demonstrated the highest precision (deviations < 0.20%). Additionally, bulk moduli were calculated using the same functionals and verified with the experimental bulk modulus of SrTiO$_{3}$ (183 $\pm$ 2 GPa, Pulse-Echo method). The predicted bulk moduli exhibited a slow, linear increase with increasing Mn. The best correspondence with the experimental bulk modulus was achieved by PBEsol and WC (deviations < 0.7%). These findings highlight the reliability of PBEsol and WC functionals for accurately modeling structural properties of SrTi$_{1-\mathit{x}}$Mn$_{\mathit{x}}$O$_{3}$ perovskites, having better precision than commonly employed LDA and PBE functionals.