Steffi Arzt
A new program from the Daresbury Laue Software Suite for Laue data processing has been accepted as an associated program with CCP4 and is now available from the CCP4 site.
The program LSCALE scales and normalizes raw integrated X-ray and neutron Laue intensity data to yield fully corrected structure amplitudes. It unites and improves the fuctions of the older programs.
LAUENORM and LAUESCALE formerly used for Laue data processing. The wavelength normalisation curve is calculated with Chebyshev polynomials. It can be derived internally from the Laue data using symmetry equivalent data recorded at different wavelengths or as an alternative by scaling the Laue data to a reference e.g. monochromatic set of data. The wavelength normalisation can be carried out for up to five wavelength ranges. The Chebyshev polynomials handle even undulator data very well.
The program also enables a wavelength and position dependent absorption correction to be calculated by two-dimensional Chebyshev-polynomials.
Harmonic multiples data may be deconvoluted again making use of symmetry equivalent data recorded at different wavelengths. When there is a measured single reflection in the equation system it will be used for deconvolution, but put in the output file with its old value.
The program provides flexibility in the control of the refinement procedure. Data input is via a control file. Refinable parameters can be refined all together in the least squares refinements or one after the other in any order. The refined scaling parameters are saved for re-use as required. On completion of the calculations the program allows a number of diagnostic tables or graphs to be output and examined and, if required, to be saved in hard copy form on an individual plot basis.
LSCALE accepts .mtz or .ge1/.ge2-files produced by LAUEGEN , the Laue intensity integration program (or modified into the required format from other sources). The scaled data may be output as .mtz and/or SHELX files with unmerged or fully merged data.
For more details see S.Arzt, J.W. Campbell, M.M. Harding, Q. Hao& J.R.Helliwell, J. Appl. Cryst. (1999) 32, in the press.
The program documentation can be
found on the CCP4 web site at http://www.dl.ac.uk/CCP/CCP4/main.html.
For a copy of the program please
contact: ccp4@dl.ac.uk.
If you have any problems or
comments,
write to Steffi Arzt (arzt@esrf.fr) or
John W. Campbell (j.w.campbell@dl.ac.uk).