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PROGRAM AVEXAR

To read ARRNGE files and prepare for LSQ with extinction

Description:

The program will read one or more of the files written by ARRNGE or ARRINC and prepare a file for LSQ in which equivalent reflections are treated independently so that a path-length dependent extinction correction can be refined. It will average reflections which have been measured more than once. If the data are intensity measurements, and "G" cards are present on the crystal data file, absorption factors will be calculated and applied. The 4 constants needed for Becker Coppens extinction corrections are no longer calculated, since this is now done when the data are read by RREFSA. The data are written in a form suitable for input to the CCSL least squares programs (SFLSQ, MAGLSQ etc.).

Input:

The crystal data file must contain:
S cards giving the symmetry
A C card with the cell dimensions
An I DTYP card describing the type of data (the same as used for
ARRNGE) it is only used to determine whether the data are flipping ratios or intensities and how many additional parameters such as angles were stored by ARRNGE

D cards describing the diffraction geometry, the wavelength and UB matrix
may be on the arranged data file.

G cards describing the crystal shape. These are optional and if absent no
absorption corrections will be made and a constant path length of 2mm will be assumed.

If the data are for a magnetic structure with non-integer indices a Q PROP card giving the propagation vector is required.

Basically the same crystal data as that used with ARRNGE to produce the input file should be used but with the addition of E, D and G cards . The data input is a file written by one of the ARRNGE type programs.

Output:

The usual listing file reporting data read from the CDF. A file of averaged and (possibly absorption corrected) data suitable for input to one of the least squares programs L MODE 5 for integer indices and L MODE 8 for floating indices. This file has default extension .sf for structure factors and .fr for flipping ratios.

Notes:

This program replaces the three similar programs ABSEXF, ARREXF and AVEXTR

Running the program:

On running the program the user is asked for the name of the crystal data, that of the arranged data file and a possible scale factor. This latter is to allow data on very different scales to be scaled to approximately the same level,if no scale is gicen a scale of unity is assumed. Several data sets may be processed in the same run.

Calls:

ABSOUT ARRHED ASK CLOFIL DUMMY ERRMES FILNOM ICDFMT INPUAR INPUTI LENG LENGT NOPFIL ONCARD PREFIN RDREAL RDWORD RECIP SAYS SETABS SETDC SYMOP

Common blocks used:

/ABSDAT/ to use all members
/DGEOM/ to use UM
/IOUNIT/ to use LPT ITO IPLO LUNI
/REFS/ to use SCALE INC ITEMS
/SCRACH/ to use all members

*** AVEXAR updated by PJB October 2008 C4.12 Read and write headers ******

Classification:

Data Collection and Reduction . . . . . . . Main Program

SUBROUTINE ABSOUT(LOUT,DOABS,ISFLIP,ASYM)

Calls:

ABSOR GMEQ INDFIX WTMEAN

Called by:

AVEXAR

Common blocks used:

/DIRCOS/ to use all members
/IOUNIT/ to use LPT
/REFS/ to use LL SCALE INC II
/STATS/ to use WRK2

*** PATH by PJB 10 Apr 87 ***




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P. Jane Brown

Institut Laue Langevin,
Grenoble, FRANCE