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arXiv · 2601.11177

Lattice dynamics and structural phase stability of group-IV elemental solids with the r$^2$SCAN functional

Adonis Haxhijaj·Stefan Riemelmoser·Alfredo Pasquarello
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Abstract

The strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (meta-GGA) functional is a milestone achievement of electronic structure theory. Recently, a revised and restored form (r$^2$SCAN) has been suggested as a replacement for SCAN in high-throughput applications. Here, we assess the accuracy and reliability of the r$^2$SCAN meta-GGA functional for the group-IV elemental solids carbon (C), silicon (Si), germanium (Ge), and tin (Sn). We show that the r$^2$SCAN functional agrees closely with its parent functional SCAN for elastic constants, bulk moduli, and phonon dispersions, but the numerical stability of r$^2$SCAN is superior. Both meta-GGA functionals outperform standard GGA (Perdew-Burke-Ernzerhof) in terms of accuracy and approach the level of common hybrid functionals (Heyd-Scuseria-Ernzerhof). However, we find that r$^2$SCAN performs much worse than SCAN for the $\alpha\leftrightarrow \beta$ phase transition of both Ge and Sn, yielding larger phase energy differences and transition pressures.

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Adonis Haxhijaj, Stefan Riemelmoser, Alfredo Pasquarello. 2026-01-16. Lattice dynamics and structural phase stability of group-IV elemental solids with the r$^2$SCAN functional. https://doi.org/10.1103/znkf-3g37

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