Spin-Crossover From a Well-Behaved, Low-Cost meta-GGA Density Functional

TL;DR

This paper demonstrates that the r$^2$SCAN meta-GGA functional improves spin-crossover energy predictions over SCAN, with a faster deorbitalized version suitable for both molecular and periodic systems.

Contribution

It introduces and evaluates the r$^2$SCAN functional and its deorbitalized version r$^2$SCAN-L for accurate and efficient spin-crossover energy calculations.

Findings

r$^2$SCAN outperforms SCAN in spin-crossover energy accuracy

r$^2$SCAN-L offers similar accuracy to SCAN with increased speed

A combined approach balances molecular and periodic system treatments

Abstract

The recent major modification, r$^2$SCAN, of the SCAN (strongly constrained and appropriately normed) meta-GGA exchange-correlation functional is shown to give substantially better spin-crossover electronic energies (high spin minus low spin) on a benchmark data set than the original SCAN. The deorbitalized counterpart r$^2$SCAN-L is almost as good as SCAN and much faster in periodically bounded systems. A combination strategy for balanced treatment of molecular and periodic spin-crossover therefore is recommended.