Energy Calculations Based on Molecular Models

7 COMPUTERIZED ENERGY CALCULATIONS BASED ON MOLECULAR MODELS 

The surveys above include 315 experimental determinations of the linkage geometry, so the question of the shape of the cellulose molecule might be considered to be answered. Almost all of the linkage geometries are in a small region of 9, j/ space that corresponds to cellulose molecules with two to three residues per helix 

One approach to these questions is to construct an energy surface or map. Such maps show the relative value of calculated potential energy at all locations in q), j/ space. The regions of lowest energy, e.g., within the 1 kcal/mol contours, should contain a large fraction, perhaps the majority, of structures that are already observed if the maps are to be considered predictive. To make such a map, the values of 9 and / for the molecule in question are stepped over a grid 

We do not know why the lactose-protein complex structures have a much wider range of conformations. At this time we cannot say that they are less accurately determined than the complexes of proteins and cellodextrins. 

Despite the apparent simplicity of these analogs, reproduction of these analog QM surfaces with general empirical force fields is difficult (Lii et al. 2005). 

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