Jilin As far as I'm aware there is no repository for Topas str files. Bruker does sell a (fairly) comprehensive set for those without the time or inclination to make their own. Topas will import CIF files, but the ICSD doesn't always export CIF files in the same format as Topas is expecting. Consequently you sometimes have to edit the CIF file by hand. Sounds tedious but it's better than typing in a 100+ atom cell by hand! I suppose someone could create such a repository, but some mineral structures do vary somewhat (occasionally alarmingly so) in the literature and I would be wary of saying that the one I use is the 'correct' one.
Pam Dr Pamela Whitfield CChem MRSC Energy Materials Group Institute for Chemical Process and Environmental Technology Building M12 National Research Council Canada 1200 Montreal Road Ottawa ON K1A 0R6 CANADA Tel: (613) 998 8462 Fax: (613) 991 2384 Email: <mailto:[EMAIL PROTECTED]> ICPET WWW: http://icpet-itpce.nrc-cnrc.gc.ca -----Original Message----- From: Jilin Zhang [mailto:[EMAIL PROTECTED] Sent: June 4, 2004 9:28 AM To: [EMAIL PROTECTED] Dear Dr. Whitfield: It appears to me you are using koalariet or topas by Dr. Coehlo et al. Do you know a web site where we can down load a bunch of .str files for minerals, as BGMN.de has the .str files for BGMN. Thanks. jilin zhang omni labs 8845 fallbrook houston tx 77064 phone 832-237-4000 -----Original Message----- From: Whitfield, Pamela [mailto:[EMAIL PROTECTED] Sent: Friday, June 04, 2004 8:15 AM To: '[EMAIL PROTECTED]' Nandini The best people to reply on behalf of fundamental parameters would be Alan Coehlo or Arnt Kern. But until they do here goes.... The more general form is convolution-based profile fitting. This can be used for all peak profile types, whereas 'pure' fundamental parameters has only been inmplemented for the simple Bragg-Brentano case (no monochromators). Other geometries have to be empirically modelled using a standard and some sort of user-defined convolution on top of the source profile. Better fits can often be obtained using this type of fitting than the normal pseudo-Voigt or Pearson VII functions (in my experience at least). Where convolution-based fitting really comes into its own in in complex quantitative Rietveld analysis where the number of refined variables would become untenable for normal peak fitting. Using convolution-based fitting it is possible to cope with upwards of 10 phases with severe peak overlap and still get good results with good stability. For example, quantitative Rietveld analysis of cements is becoming routine. Pam Dr Pamela Whitfield CChem MRSC Energy Materials Group Institute for Chemical Process and Environmental Technology Building M12 National Research Council Canada 1200 Montreal Road Ottawa ON K1A 0R6 CANADA Tel: (613) 998 8462 Fax: (613) 991 2384 Email: <mailto:[EMAIL PROTECTED]> ICPET WWW: http://icpet-itpce.nrc-cnrc.gc.ca -----Original Message----- From: Nandini Devi Radhamonyamma [mailto:[EMAIL PROTECTED] Sent: June 4, 2004 6:42 AM To: [EMAIL PROTECTED] Dear All, Is the fundamental parameter approach better than mathematical approach used in most of the Rietveld refinement programs? Does that mean programs which use that approach are better? Any suggestions? Nandini __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/
