PW calculations in VASP used the projector-augmented wave (PAW) method and standard pseudopotentials with a planewave energy cutoff of 600 eV and maximum k-point spacing of 0.05 Å -1 . GTO calculations in CRYSTAL17 employed different basis sets and composite methods, details of which are described in Section 3.2. Electronic k-points were sampled uniformly to a resolution of at least 0.02 Å -1 . Truncation criteria for bielectronic integrals, TOLINTEG, of 12 12 12 12 24 was enough for good convergence in most of the structures, however, there were cases that we had to increase these values to 14 14 14 14 28.