MatPESStaticSet.yaml set LMAXMIX: 6

[janosh]

LMAXMIX controls expansion of the charge density up to spherical harmonics of order $Y_{lm}$ with $l$ = LMAXMIX, $l$ = 2 for p-block, 4 for d-block, 6 for f-block, etc.

Internal benchmarking by @esoteric-ephemera found little run time cost but improved energies from LMAXMIX = 6. See pages 7 and 8 in 2023-09-27-kaplan-bench-vasp-params.pdf.