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Billy Wayne McCann, PhD.
bed9812e15
mmffstbn.par was missing the class-2 stretch-bend entry for atom types (2,2,2) (sp2 carbon center with both bonds BT-flagged) that is present in the original MMFF94 parameter set. Without it, class-2 C(sp2)-C(sp2)-C(sp2) angles fall through to the MMFFDFSB default (0.30/0.30) instead of the fitted values (0.219/0.250). Verified against an independent transcription of the original file (Tinker's mmff94.prm): it is the only missing entry among 283, with no value differences in the rest. Energy impact on the Halgren validation suite (JIYJAC): stretch-bend 0.2368 kcal/mol vs 0.1858 from the original BatchMin program; matches to 4 decimals once the entry is restored. Inserted after the class-1 (2,2,2) entry to preserve the canonical CXBA ordering. Fixes #3003
Open Babel
Open Babel is a chemical toolbox designed to speak the many languages of chemical data. It's an open, collaborative project allowing anyone to search, convert, analyze, or store data from molecular modeling, chemistry, solid-state materials, biochemistry, or related areas.
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