Molecular torsion angle deformation

Williams and Lawton have presented a graphical comparison of the equivalent torsion angles in the 12-membered central ring of TOT for three different crystalline species the ethanol and n-cetyl alcohol TOT inclusion compounds, and the unsolvated TOT. This comparison was instructive because it revealed a fairly consistent molecular deformation in three different crystalline environments. A rationale for this structural feature is not readily apparent. 

All calculations are based on mechanical molecular models the atoms are more or less deformable spheres, the bonds are rigid springs. Attraction and repulsion are calculated separately as a function of the torsion angle. A typical exercise, for example, proceeds from the total energy of an ethane molecule, which is made up of five components (Figure 4-4) ... 

In the molecular dynamics simulations presented here, the energies of the solute molecules were evaluated using an empirically based Hamiltonian, fftotau which consisted of a sum of individual contributions arising from bond stretching, deformation of valence and torsional angles, as well as Lennard-Jones and Coulomb interactions between... 

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