[ccp4bb]: DM does not want to be my friend

[Stephen Graham <stepheng@mail.usyd.edu.au>]

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Hi

I am having some issues with using DM for averaging to improve the phases
of a molecular replacement solution.  The structure I am solving is of an
inhibitor soak of a known structure, but in a different space group.
Specifically, I am working with a tetramer in the C2221 space group.  There
are 6 monomers in the asymmetric unit (one tetramer is formed by 222 NCS and
the other is formed by 2-fold NCS and 2-fold crystallographic symmetry).
I obtained good MR solutions (to 4 A) with AMoRe, and did a rigid body fit with
REFMAC5 (treating each monomer as a rigid body, Rfree after fit was ~30%).  
I created a mask for one monomer using NCSMASK and the known structure.  This
mask looks good (on inspection in O).

When I try to run DM I find that:
  a) It can not determine the correct number of NCS monomers.  DM
  guesses that I have 2 (which I think is wrong, I would say 4 or 8 but
  am myself not sure).
  b) The mask seems to be changing after every round (even though I
  have not asked for this to happen) which I do not really want as the
  mask I have generated should be quite accurate.

Eeep!  Following is my DM input script. Any help would be most welcome.

Thanks in advance,

Stephen

--
#!/bin/csh -f

dm  HKLIN ain_refmac_rigid_1.mtz \
    HKLOUT ain_dm.mtz            \
    NCSIN1 ain_dm_ncsmask.msk    \
        << EOF | tee dm.out

MODE SOLV HIST MULT AVER
SOLC 0.7243
NCYCLE 10
COMBINE NOCOMBINE
SCHEME AUTO
LABIN FP=F SIGFP=SIGF PHIO=PHIC FOMO=FOM
AVERAGE REFI
ROTATE POLAR 0.00000     0.00000     0.00000
TRANSLATE   0.000000  0.000000  0.000000
AVERAGE REFI
ROTATE POLAR 173.48286   -46.13584   179.63538
TRANSLATE   0.578133  0.461114 -0.012293
AVERAGE REFI
ROTATE POLAR 84.24913   -67.42525   179.36342
TRANSLATE   0.721613  0.218351  0.333384
AVERAGE REFI
ROTATE POLAR 87.58064    22.91057   179.70605
TRANSLATE  -0.176813  0.263717  0.241579
AVERAGE REFI
ROTATE POLAR 86.11459   -33.78910   179.83943
TRANSLATE   0.710235  0.767602  0.132263
AVERAGE REFI
ROTATE POLAR 88.82640  -123.84518   174.14796
TRANSLATE   0.290691  0.236026  0.158956
END

EOF

-- 
Stephen Graham
PhD candidate and nasty sysadmin
Crystallography Group
School of Molecular and Microbial Biosciences
Building G08
University of Sydney
New South Wales, 2006
Australia
Ph: +61 2 9351 8197
Fax: +61 2 9351 4726