SCALE s :

This keyword defines how finely the molecular transform will be sampled : If p, q, r are the dimensions (in Å) of the smallest orthogonal box that can fully enclose the search model, then QS will calculate the molecular transform by placing the model in an orthogonal cell with dimensions sp, sq, sr, followed by Fourier transformation of the corresponding electron density distribution. The higher the value of s, the finer the transform will be sampled, the more physical (computer) memory you need for storing the transform. On the other hand, the finer the sampling the higher the accuracy of the calculated F_c values. I think that you should aim for a value of SCALE of at least 4.0. If you have enough physical memory it may be a worth-while exercise to try to increase SCALE to about 8.0 and to give INTErpolation_scheme NONE (see below). The keyword GRAUto will attempt to automatically determine suitable values for both SCALE and MAXGridspacing, aiming for a value of SCALE of 4.0.