Intermolecular Potentials and Force Fields

The alternative route to intramolecular potentials, by crystal-packing studies, has been adopted for small hydrogen bonding moleeules. In a force field, lone pairs may be represented as electrostatic interactions, or by modifying torsional potentials.  

A few days computing time was required for minimal basis set SCF-MO calculations on o-glucose and /5-maltose. Energy differences for a- and /ff-D-glucopyranose and for two conformers of /5-maltose were found in the correct 

dementi, Computational Aspects for Large Chemical Systems , Lecture Notes in Chemistry, Springer, Berlin, 1980, Vol. 19. 

In two current reviews, where intramolecular hydrogen bonds of peptides and the reverse turn structures of proteins are discussed, and reference is made to relevant conformational calculations, the point is made that water has a fundamental influence upon the organization of protein molecules. Scheraga has reviewed previous attempts to understand solvent effects and incorporate them into computer models of small and polymeric molecules.  

Suter has described the considerations which apply to the development from the conformational analysis of small molecules of a semiempirical force field for a new type of polymer structural unit. The force field thus chosen was based upon aldehydes and ketones, and was ultimately applied to poly(methyl vinyl ketone). 

Warshel, in Modern Theoretical Chemistry , ed. G. A. Segal, Plenum, New York, 1977, Vol. 7. 

Niketic and K. Ramussen, L.ecture Notes in Chemistry , Springer-Verlag, Berlin, 1977, Vol. 3. 

Allinger, J. Amer. Chem. Soc., 1977, 99, 8127 and references cited therein, 

Statistical Mechanics of Chain Molecules , Interscience , New York, 1969 

Tadoroko et al. provide a new method for the calculation of the elasticity of an isolated helical chain and the distribution of strain energy to the internal co-ordinates under conditions that the rotational angle per monomer is constant. For the calculation of three-dimensional elastic constants, the space group symmetry of the unit cell may be used to reduce the memory size required for polymers such as poly(vinyl alcohol) which have unsymmetrical repeat units. The constraints imposed upon tie molecules in semi-crystalline polyethylene are considered to restrict them to three conformations, the deforma- 

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