All, We seem to have stumbled upon a problem in sfall. The two attached pdb files are nearly identical, except the coordinates and b-factors for the two atoms are swapped. When calculating Fs with sfall, we get drastically different mtz files. Upon calculating the corresponding Fcalc maps, it seems that the second atom in a.pdb gets ignored, whereas both atoms in b.pdb are included. There is nothing obvious in the log files to hint to what is happening (i.e. both files state "Number of atoms input = 2 Number of atoms in sort = 2 Number in density generation = 2 Number completely within fft box = 2 Minimum B = 5.91 Maximum B = 5.97 Average B = 5.94 " We observed this behavior on mac and on Linux.
Cheers, Jens
a.pdb
Description: application/aportisdoc
b.pdb
Description: application/aportisdoc