You are absolutely right! The difficulty in getting from MTZ to any
other format or back is unacceptable. Expecting working
crystallographers to write Fortran format statements is ridiculous. I've
been trying to address this by adding support for other formats to
clipper, but my pace has been glacial, owing to the limited academic
rewards for such work. Even then, it needs someone to put together an
application and GUI to use it with.
I will try and remember to raise this issue at the CCP4 developers
meeting this year. If you prod me in April and I'll report back to the BB.
Kevin
George M. Sheldrick wrote:
Dear Ian,
It is all part of a diabolical CCP4 plot to make it as inconvenient as
possible to move from a REFMAC refinement to SHELXL! I hope that i do
not get excommunicated like DVD for this comment.
To summarize your and Martin's suggestions, I know of only two ways to
move from mtz to hkl:
=====================================================================
1] run mtz2various with the keywords:
LABIN FP=FP SIGFP=SIGFP FREE=FreeR_flag
OUTPUT SHELX
FSQUAR
then edit the resulting .hkl file with any text editor to remove the
header (which SHELXL cannot read) and all occurences of the word 'FREE'.
I have from time to time suggested that mtz2various be changed so that
it no longer outputs the extra junk, but it is still there (at least in
CCP4-6.0.2).
This produces an 'inferior' SHELXL HKLF4 format file because the
intensities and their standard deviations have been converted to F and
back to I, which requires the assumption of an intensity distribution
function that may not be completely valid (e.g. if NCS is present) and
so produces inferior sigma(I) values. In practice one can live with
this, but it is not very scientific.
=====================================================================
2] Use Tim Gruene's mtz2sca to convert from .mtz to .sca.
mtz2sca name
reads name.mtz and writes name.sca. This program is avaliable from Tim
or from the SHELX download area (Linux only). This has the advantage
that it uses intensities if it can find them in the .mtz (e.g. if they
are still there from SCALA) and otherwise uses F's. mtz2sca is fine if
you want to do exprimental phasing (e.g. read the data into SHELXC
either directly or via Thomas Schneider's hkl2map) but unfortunately
.sca format does not know about Free-R flags. So, as Martin suggested,
one can read the .sca file into xprep (start xprep without a file name
and give the full name of the .sca file when prompted) and then use the
xprep option to transfer the Free-R flags from the 'inferior' .hkl file
from mtz2various and write it out in SHELXL HKLF4 format. This produces
a slightly better file for refinement when the .mtz file contains
intensities, but requires xprep.
====================================================================
George
Martin Hallberg wrote:
I would probably prioritize keeping the same R-free set (thus using
the F^2 output by mtz2various) over
going through the scalepack format and loosing track of it.
You can however use XPREP to transfer the R-free set from the
"inferior" F^2 HKLF4 file output by mtz2various to the proper
intensities read from the scalepack file generated by mtz2sca. Then
you can write out an HKLF4 file for refinement in SHELXL-97. That
HKLF4 file will have proper intensities and the same Rfree set that
you have used in Refmac5 (or perhaps Restrain?). But then one would
wish that mtz2various did this from the beginning...
Best regards,
Martin
On Mar 1, 2007, at 7:58 PM, Ethan Merritt wrote:
On Thursday 01 March 2007 10:17, Ian Tickle wrote:
All, I thought this would be a simple task, but for the life of me I
can't see how to do it! All I want to do is convert an MTZ file to
Shel-X format for refinement. I thought it would take me 2 secs, but
it's taken me at least 5 attempts, and it's still not right!
Do the conversion on the shelx side, rather than the CCP4 side.
http://shelx.uni-ac.gwdg.de/~tg/mtz2sca/mtz2sca.html
.
B. Martin Hallberg, PhD
Molecular Cell Biology Program
Department of Cell and Molecular Biology
Karolinska Institute
Nobels väg 3
SE-171 77 Stockholm
