Hi Eleanor, I hate to disagree with you, even partially, but it depends on whether or not you're doing phase combination with external phases. In the usual case with just model information, SIGMAA doesn't take the absolute value of 2mFo-DFc so it can be positive or negative and goes with the original PHIC. When phase combination is carried out, then the phase of the map coefficient is different from any of the input phases, and FWT has to be combined with PHFWT.
There's a discussion in the documentation: http://www.ccp4.ac.uk/html/sigmaa.html#files. Regards, Randy On 11 Aug 2010, at 10:52, Eleanor Dodson wrote: > Actually I think it needs the labels FWT PHWT > > I may be wrong but like REFMAC I think it outputs a ositive FWT and PHWT is > either equal to PHIC or to PHHIC+180, depending on the sign og > FWT = (2m|Fo| - D|Fc|) > > > Eleanor > > > Hailiang Zhang wrote: >> Dear Tim: >> This is also what I thought. Thanks! >> Best Regards, Hailiang >>> Dear Hailiang, >>> >>> the man-page of sigmaa claims >>> FWT (2m|Fo| - D|Fc|) exp(i AlphaCalc) >>> Analogous to 2Fo-Fc map, FFT input: F1=FWT PHI=PHIC >>> ^^^^^^^^^^^^^^^^^^^^^^^^^^ >>> so I would leave out WCMB. >>> >>> Tim >>> >>> On Tue, Aug 10, 2010 at 01:33:11PM -0400, Hailiang Zhang wrote: >>>> Hi there: >>>> >>>> When I generate the mtz file by SIGMAA, and want to view the 2mFo-DFc >>>> map >>>> in coot, should I choose "FWT PHIC WCMB" combination or just "FWT PHIC"? >>>> I >>>> think the later is more reasonable and I did see somebody the former as >>>> well. Didn't see explicit instruction in SIGMAA document, and I >>>> appreciate >>>> for any hint. >>>> >>>> Best Regards, Hailiang >>> -- >>> -- >>> Tim Gruene >>> Institut fuer anorganische Chemie >>> Tammannstr. 4 >>> D-37077 Goettingen >>> >>> GPG Key ID = A46BEE1A >>> >>> ------ Randy J. Read Department of Haematology, University of Cambridge Cambridge Institute for Medical Research Tel: + 44 1223 336500 Wellcome Trust/MRC Building Fax: + 44 1223 336827 Hills Road E-mail: [email protected] Cambridge CB2 0XY, U.K. www-structmed.cimr.cam.ac.uk
