Contour energy values, GRID

Grids of target-probe interaction energy values can be read into many molecular graphics programs which can display the MIFs as isoenergy contours or project the energies onto molecular surfaces. 

Quantum chemical calculations provide the values of a multi-dimensional potential at the mesh points of a grid. Several coordinates are varied step by step and to each set of all these coordinates there is a corresponding number. However, we need a potential energy function which is analytic if possible, continuous and differentiable in any order. At the mesh points of the grid the values of this function are to be as close as possible to the computed ones. In addition, the values of the derivatives of this function with respect to any coordinate must be physically possible on the limiting contour surrounding the region of the potential surface studied. This is very im-... 

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... 

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