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I suspect the problem is that sftools hasn't been modernised to alter all the cell dimension records used in current MTZ files. I can't remember right now but maybe the DCELL command in cad might fix it. Randy Read ---- Randy J. Read > On 2 Oct 2013, at 17:13, wtempel <[log in to unmask]> wrote: > > Hello, > I would like to expand a reflection data set in mtz format from C2221 to P21. The purpose is to obtain consistent R-free flags based on a structure already refined in C2221 for a related data set that I suspect is pseudo-C2221 but "real" P21. > > Primitive cell dimensions are: 37.6 126.1 40.61 89.99 117.6 90.01, > C-centered: 37.6 71.99 126.1 90 89.99 90.01 > pointless provides the following matrix: > <pointless> > Reindex operator from input cell to lattice cell: [h,h+2l,-k] > > h' = ( h k l ) ( 1 1 0 ) > ( 0 0 -1 ) > ( 0 2 0 ) > > </pointless> > In sftools, I loaded the C2221 data set and did > > sftools$ reindex matrix 1 0 0 0 0 -1 -.5 .5 0 > > with the transposed (to account for the presumably inverted order of factors in the program?) inverse matrix of the one listed above with the aim of restoring the primitive asymmetric unit. > I was encouraged seeing sftools report new cell dimensions matching the expected primitive cell. > Then I did > > sftools$ expand 4 > > I expected now to have a "workable" P21 version of my C2221 data set, but molecular replacement (MOLREP) with my C2221 model failed to place even a single copy of the model. > Thus, I must have misused sftools by issuing commands that were either wrong or in the wrong order or my application of linear algebra was mistaken. > Any ideas out there? > Thanking you in advance, > Wolfram Tempel