PROGRAM SORGAM

Calculation of gamma and magnetic structure factors from flipping
ratios

Description:

SORGAM calculates the magnetic structure factors from a set of flipping ratio measurements which have been sorted by ARRNGE. The program assumes that there is a unique magnetisation direction which by default is parallel to the Z axis of the diffractometer which is the polarisation direction.
Corrections are made for the inclination of the scattering vector to the x-y plane and for extinction if an E card is present. The gamma values of equivalent reflections are averaged, weighted according to their esd's.

Input:

The crystal data file, which must contain:

S cards giving the symmetry.
A C card with the cell dimensions.
A cards defining the atoms, their positions and isotropic. temperature factors.
F cards giving the scattering factors

optionally:

T cards giving anisotropic temperature factors
G cards giving the size and shape of the crystal (for path length

calculations)

An E card giving the extinction parameters

Additionally:

A P card giving the polarisation
D cards giving the crystal orientation,

an optional D LAM2 card giving the half wavelength contamination as a fraction of the full wavelength intensity.

The P and D cards can be copied from the file dcards.cry written by D3OP97

I cards which should be the same as those used for ARRNGE but can

include the extra words OUTP GAMA, MAGD, X, Y, Z, PHI
OUTP 100 causes a file SORCOR.LIS to be written which gives all the

correction factors

GAMA 1 indicates that there are reflections for which \$\gamma \> 1\$

ie the magnetic scattering is greater than the nuclear. (default 0)

MAGD defines the magnetisation direction

MAGD = 1 (default) magnetisation parallel to omega axis
MAGD = 2 magnetisation parallel to an axis given on an I card

by numbers following the words X, Y, and Z

MAGD = 3 magnetisation between 1 and 2 at

\$\cos^{-1}(\cos\phi)\$ to 2. Where \$\phi\$ follows the word PHI on an I card

MAGD = 4 Schwinger scattering

A file of sorted flipping ratios as written by ARRNGE. Default extension .arr
If GAMA = 1 a file containing the indices of reflections for which \$\gamma > 1\$. This may be followed by the value of \$\cos\rho\$ below which the effective \$\gamma < 1\$. (\$\rho\$ is the angle of inclination of the scattering vector to the x-y plane of the diffractometer). These indices must be given in the standard order of ARRNGE files ie sorted in order of increasing \$\ell\$ then \$k\$, then \$h\$.

Output:

A listing file sorgam.lis which reports what as read from the crystal data file and gives the calculated \$\gamma\$ values for each set of equivalent reflections. The mean \$\gamma\$, its esd, \$\sinth\$, the nuclear structure factor and the experimental magnetic structure factor with its esd are given for each reflection in the asymmetric unit.
If OUTP = 100 a file SORCOR.LIS which lists the extinction factor, and the correction factors \$\{\bf q\}\cdot \{\bf q\}\$ and \$\{\bf q\}\cdot\{\bf\lambda\}\$. \$\{\bf q\}\$ is a unit vector parallel to the projection of the magnetisation direction on the plane perpendicular to the scattering vector and \$\{\bf \lambda\}\$ is a unit vector parallel to the polarisation direction. a file containing \$hkl\$ \$\gamma\$ and its esd and/or one containing \$hkl\$ and the observed magnetic structure factor with its esd for each reflection in the asymmetric unit.

Notes:

SORGAM will make a \$\lambda/2\$ correction If a D LAM2 line is included in the cdf

Running the program:

On running the program the user is asked for the name of the crystal data file, then whether output of \$\gamma 's\$ and/or magnetic structure factors are required. If GAMA = 1 the name of the file containing the indices of reflections with \$\gamma \> 1\$ is requested.
Finally the name of the data file containing the flipping ratios is required (default extension .arr).
The output files are named with the leaf name of the data file and extension .gam for \$\gamma 's\$ and .msf for magnetic structure factors.

Calls:

ABMULT ASK CENTRE EXTPAR FGAMMA FILNOM GAMEX GMEQ GMSCA ICDFMT INDFIX INPUAR INPUTI LENG MESS NEWLIN NOPFIL PREFIN SAYS SETABS SETDC SETFC SETPOL STATIS VCTMOD WTMEAN

Common blocks used:

/ABSDAT/ to use MODEA

/CARDRC/ to use ICRYDA

/DGEOM/ to use ALAM2

/EXTN/ to use IEXTYP EXTCOR CEXT

/IOUNIT/ to use LPT ITO IOUT

/REFS/ to use LL SCALE INC II FF ITEMS

/SCRACH/ to use all members

/WHEN/ to use DATIM

*** SORGAM updated C129 by PJB Feb 2004 ***

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

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P. Jane Brown e-mail: brown@ill.fr
Institut Laue Langevin,
Grenoble, FRANCE