A Phi-Fano Bond Ledger for Gas-Phase Atomization Energies: Parameter Compression, Matched C-Halogen Substitution Increments, and Hash-Locked Prediction Registers

This record contains Paper 051 of the Enumiaze Research Program: a bounded computational thermochemistry audit of a phi-Fano molecular bond-energy ledger for gas-phase atomization energies at 298.15 K. The paper reports two principal findings. First, on an identical 30-molecule primary set, the U131 V11 ledger achieves 2.160% MAPE using a small algebraic parameter ledger, while a conventional mean-bond-energy-contribution baseline remains more accurate at 0.892% MAPE. The broad claim is therefore parameter compression, not raw-error superiority. Second, after subtracting the shared alkyl backbone in matched terminal C-halogen pairs, the V31 source-complete audit reaches 10 substitution increments and gives U131 3.136% MAPE versus 4.347% for the tested MBEC increment baseline, with a 99.5% exhaustive subset-win fraction. The record also documents hash-locked prediction registers for future homologous-series validation. The manuscript separates formula-generated predictions, source-complete scoring, diagnostic failures, and pre-registered unscored rows.