• converts reflection data files as obtained from xds or xscale into various formats required by software packages for crystal structure determination like CNS (X-PLOR), SHELX, or CCP4,
  • uses a Bayesian approach to statistical inference for estimating structure factor moduli from the reflection intensities (French and Wilson, 1978),
  • can inherit test-reflections previously used for the calculation of the free R-factor,
  • can select new test-reflections that are outside the resolution range covered by the inherited test-reflections - a feature used if new data at higher resolution become available that should be included in the structure refinement process.

The program uses two files with a fixed name.

XDSCONV.INP
contains the input parameters (see section Input Parameters) you have to provide to run the program. This file is mandatory and must reside in the current directory from which XDSCONV is called.
XDSCONV.LP
is generated by XDSCONV and reports the results and diagnostics from running the program.

Example for XDSCONV.INP

Assume that three data sets, named ip.ahkl, pk.ahkl, and rm.ahkl (see Example for XSCALE.INP), are available from a selenomethionyl protein crystal at different wavelengths and that you want to carry out the subsequent structure analysis by the CNS package.
For conversion of the files to structure factor files for input to CNS you make a separate run of XDSCONV for each of the three xscale files. The input parameter values for XDSCONV.INP are shown below for the conversion ip.ahkl --> ip.cv .

SPACE_GROUP_NUMBER=5
UNIT_CELL_CONSTANTS=228.366 69.910 113.550 90.0 97.57 90.0

!name, type, and resolution window for accepting reflections
INPUT_FILE=ip.ahkl  XDS_ASCII 20 2.5

!File-name, target software-package, and validity of Friedel's law
OUTPUT_FILE=ip.cv  CNS    FRIEDEL'S_LAW=FALSE !TRUE

!Specify whether intensity data obey Wilson statistics or not.
!WILSON_STATISTICS=FALSE !TRUE   !Default is TRUE

In a similar way the other two data sets, pk.cv and rm.cv, are obtained by running XDSCONV after the appropriate changes to XDSCONV.INP have been made. The converted files ip.cv, pk.cv, and rm.cv may then be used directly for input to CNS (CNS input file "merge.inp").

Wolfgang Kabsch 
page last updated: September 1, 2002