> Oh, goodness, I see: even here, we would need clear rules what the > calculated structure factors are, which weights are were, which bulk solvent > correction was applied ... a maze, too!
Fortunately the X-ray & restraint weights/target values are not an issue here: varying them changes the refined model parameters of course, but they do not appear in the structure factor formula, so don't need to be specified in the mathematical model to obtain the Fcalcs. You would of course need to know all the weights & target values (as well as the SF formula) to reproduce the refinement to get the deposited model. > But could future programs really re-calculate the same structure factors > from the deposited model? Because of the expected development of more > advanced methods and algorithms, I have my doubts ... *sigh* Yes, if the deposited mathematical model is completely specified in terms of the SF formula used and the values of *all* the parameters that go into it, then in principle future versions of software using more advanced models will be able to reproduce the exact Fcalcs. This assumes that the advanced models will use the same 'core' formula but with additional terms and adjustable parameters, so that the simple model can be obtained from the advanced one by constraining the extra parameters to fixed values. However if the simple model is not 'nested' inside the more advanced model in this way, then no it will not be possible to reproduce the Fcalcs. However as I implied, the main issue is that we're rather lax at fully specifying our models (both formulae & parameters): obviously if in future you don't have all the information you need to reproduce the calculation then you have no hope of getting the same Fcalcs! Cheers -- Ian
