README.TXT for the Absorption package

This package is a set of subroutines, with one driver program,
for calculating anomalous dispersion corrections, atomic form 
factors, scattering cross sections and complex structure factors.
In the following description, the names of the subroutines will be 
in parentheses.  Included in the package is the help file from
the VMS version which lists all the subroutines and the calling 
sequence for each routine.  The routines for f' and f'' are based 
on theoretical work of Cromer and Liberman (abs$cromer).  The 
Rayleigh and Compton cross-sections are based on McMaster 
(abs$raycomp).  Hydrogen and Helium data are McMasters for 
photo-electric effect as well as Rayleigh and Compton. There is 
also a routine for calculating the form factor f(k) using 
theoretical work of Cromer and Mann (abs$sfcoef).  This same 
routine calculates the angular dependence of the compton 
scattering using the parameterization of Balyuzi.

There is a driver program (absorb) for calculating the absorption 
of elements, crystals and materials.  There is also a subroutine
(abs$struct_fact) for calculating the complex structure factor for 
crystals.  Included is a VMS build.com, an MPW .make file, and 
several example crystal and material definition files.

Originally  written for VMS, the routines are now standard f77 and
compile on Macs (MPW) and most unix machines.  These routines are
in use at APS, ESRF, and Hasylab as well as here at SSRL.

An earlier version of this work is described in
S. Brennan and P.L. Cowan
"A suite of programs for calculating x-ray absorption, reflection and
diffraction performance for a variety of materials at arbitrary
wavelengths" Rev. Sci. Instrum., 63, 850 (1992).

The absorption package is available via anonymous ftp to :-
sol.dmp.csiro.au/pub/xtallography/absorb

README.TXT (this file)
absorb.tar
absorb.sit.hqx

The latter includes a Mac executable of the driver for calculating
absorption lengths.  

If anyone out there still uses VMS, there is also available a save 
set which can be used to install the driver program and a shareable 
image library of the subroutines.  This is available both for Alphas
and VAXen.  For those of you in pc-land, at present the file names 
are all <=8 characters, but the actual subroutine names are longer.  
I am told that tar readers are readily available for PCs.  But soon
I will upload a .zip version as well.  Please send questions,
comments, bug-reports to:

Sean Brennan
Bren@slac.stanford.edu