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.