cellcheck

Abstract

First public release. cellcheck reads the lattice parameters of a crystal structure and reports whether its unit cell satisfies the minimum-image convention for a given interaction cutoff, and if not, along which axis and by how much. What it does Computes true perpendicular widths (V / |a_j × a_k|), not edge lengths. In oblique cells the edges overstate clearance: IRMOF-74-V has 39.87 Å edges but faces only 34.5 Å apart at α = 60.3°. Reports the per-axis replication n_i = ceil(2 r_c / w_i), the total replication m, and the worst-axis replication n_max. Returns a verdict: compliant / acceptable for ranking / recompute (with the uptake-error band observed for that stratum in the accompanying audit). Emits UnitCells lines ready to paste into RASPA inputs (--raspa). CSV and JSON output for screening whole libraries. Why n_max and not m Minimum-image violation fails independently along each lattice direction, so the error tracks the worst single axis, not the total number of cells. A framework needing 4×1×1 is as badly biased as one needing 4×3×3 and costs a ninth as much to fix. Rod-SBU frameworks (MOF-74, the IRMOF-74 series) fail systematically: their metal–oxygen chain fixes one lattice repeat near 6.5 Å however large the pores become. Usage python cellcheck.py structure.cif python cellcheck.py *.cif --cutoff 12.8 python cellcheck.py --cell 6.4618 39.8715 39.8715 60.2892 86.9032 93.0968 python cellcheck.py *.cif --raspa python cellcheck.py *.cif --format csv Requirements Python 3.8+. No dependencies beyond the standard library. Notes The error bands attached to each verdict are observed values from an audit of 85 CoRE MOF 2019 frameworks (H2, 77 K, 12 Å cutoff, dispersion-only) and are reported as measurements, not as guarantees; the geometry itself is exact. Accompanying manuscript in submission - reference and DOI to follow in a patch release.