Molecular Identity and the Localisation of Constraint: A TEF Analysis of Chemical Structure

Abstract Chemistry occupies a distinctive explanatory position: quantum mechanics governs electronic behaviour, yet molecular structure is definite, stable, and causally efficacious. This paper argues that the apparent tension between quantum indeterminacy and chemical definiteness dissolves once molecular identity is understood as constraint localised at finite scale. Drawing on the Triaxial Existential Field (TEF) framework, the analysis reinterprets the potential energy surface as R-register constraint operating at molecular scale, molecular identity as C-locus persistence under that constraint, and chemical reactions as constraint reconfiguration rather than mere rearrangement of substance. The Born-Oppenheimer approximation is reinterpreted not as a substance distinction between classical nuclei and quantum electrons but as a register distinction between constraint and participation. Chirality is analysed as topological asymmetry in the constraint landscape, with homochirality identified as a candidate threshold condition for biological admissibility. The paper concludes that chemistry is the regime where constraint first localises at finite scale, providing the template for all subsequent levels of structural organisation and bridging the foundational physics treated elsewhere in the TEF programme with the biological domain addressed in a companion paper.