#F CromerMann_old1968.dat #D Mon Sep 30 14:50:02 2002 #UT Parametrization of f0 (the non-dispersive part of the atomic scttering factor) vs sin(theta/lambda). #UF0TYPE PARAMETRIZATION ; TABLE OR PARAMETRIZATION? #UIDL xf0 #C This file has been created using f0_CromerMann_old1968.pro #C This file belongs to the DABAX library. More information on #C DABAX can be found at: #C http://www.esrf.fr/computing/scientific/dabax #UD Parametrization of f0 (the non-dispersive part of the atomic scttering factor) vs sin(theta/lambda). #UD #UD fo the non-dispersive part of the atomic scattering factor is a #UD function of the selected element and of sin(theta)/lambda, where #UD lambda is the photon wavelengh and theta is incident angle. #UD This function can be approximated by a function: #UD #UD f0[k] = c + [SUM a_i*EXP(-b_i*(k^2)) ] #UD i=1,4 #UD #UD where k = sin(theta) / lambda and c, a_i and b_i #UD are the so called Cromer-Mann coefficients. #UD The data contained in this file (f0_CromerMann_old1967.dat) are #UD the coefficients of the original paper: #UD X-ray scattering factors computed from numerical Hartree-Fock wave functions #UD by Don T. Cromer and Joseph B. Mann #UD Acta Cryst. (1968) A24,321 #UD #UD The data in this file has been extracted from the file sf_inc.f #UD of the library by Brennan and Cowan (S. Brennan and P.L. Cowan (1992) #UD Rev. Sci. Instrum. 63, 850) #UD The program suite described by Brennan and Cowan (1992) is #UD available by ftp from the authors from #UD http://www-ssrl.slac.stanford.edu/absorb.html or #UD ftp://ftpa.aps.anl.gov/pub/cross-section_codes/sb-1.0.tar.Z #UD #UD A more recent and accurate set of coefficients can be found in the #UD International Tables for X-ray Crystallography, vol. 4 or vol C; #UD in vol. C refer to pg 500-502). The latest coefficients are in #UD DABAX file f0_CromerMann.dat #UD #UD Note, this is only good out to sin(theta)/lambda < 1.50 [Angstrom^-1]. #UD After that, there is another functional fit which can be found on page #UD 487 (eq 6.1.1.16) in vol C of the International Tables. #UD See DABAX file f0_WaasKirf.dat for a parametrization valid in the #UD whole 0