Charge-density ionicity and Cohen-type bulk-modulus scaling in tetrahedral semiconductors

This dataset accompanies the manuscript "From Empirical Ionicity to Electronic Charge Density: Testing a Continuous Descriptor for Cohen-Type Bulk-Modulus Scaling in Tetrahedral Semiconductors" (H. Aourag, submitted to Materials Chemistry and Physics). It contains 41 canonical diamond and zinc-blende phases from the Materials Project, locked by MP-ID, formula and space group. For each phase it gives: the bond-centred charge-density descriptors: the symmetric and antisymmetric integrals I_S and I_A, and η = I_A/I_S, over three central windows; an experimental working set of bulk moduli with a provenance label for every value; the Materials Project PBE bulk moduli K_VRH for exactly the same phases (39 of 41 available). The deposit also contains the complete analysis workbook and the Python scripts that reproduce every number and figure. The analyses cover leave-one-out and leave-one-family-out cross-validation, paired bootstrap tests, window and fitting-space sensitivity, an I–VII transfer test, and a volume-factor control of the symmetric integral. Main results: With experimental moduli, the antisymmetric integral I_A reproduces the predictive content of Cohen's ionicity index λ in B = (1971 − 220λ) d^−3.5. With the homogeneous PBE target, λ remains accurate, whereas I_A does not, because the PBE error varies with I_A within the III–V family. A nominally significant gain from I_S is traced to its volume factor.