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

The recent major modification, r2SCAN, 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 as well as on some Fe complexes. The deorbitalized counterpart r2SCAN-L is almost as good as SCAN and much faster in periodically bounded systems. A combination strategy for the balanced treatment of molecular and periodic spin-crossover therefore is recommended.