I don't really understand what you are driving at, but it seems as though you want to express Diamond as a simple cubic cell with a two atom basis? Isn't that Pm3m with atoms at 0,0,0 and 1/4,1/4,1/4, or some such. I don't really understand how that will save you time in abinit, but, of course, I am not a crystallographer.... B PS. Doesn't abinit understand crystal symmetry? Why can't you just tell it that it's diamond and has the symmetry of diamond? -- Bruce Ravel ----------------------------------- bravel@bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at Brookhaven National Laboratory Building 535A Upton NY, 11973 My homepage: http://cars9.uchicago.edu/~ravel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/ -----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov on behalf of joshua jason kas Sent: Thu 6/18/2009 2:41 PM To: ifeffit@millenia.cars.aps.anl.gov Subject: Re: [Ifeffit] Primitive unit cell from .cif file Thanks everyone for your suggestions! I have tried the following things. I used atoms (webATOMS) to generate a p1.inp file using diamond as an example, but this gives me the conventional cell with 8 atoms in it instead of the 2 atom primitive cell. Am I doing something wrong? The input file came from the atoms database and the output is as follows: * * "F d -3 m" appears in the International Tables with * multiple choices of origin. If the atoms list seems wrong, you * should use a shift vector of: * -0.125, -0.125, -0.125 * * ! This p1.inp file was generated by WebAtoms 1.8 (Atoms 3.0beta10) ! Atoms written by and copyright (c) Bruce Ravel, 1998-2001 title = name: diamond title = formula: C title = sites: C1 title = refer1: Kittel, ISSP title = refer2: title = schoen: title = notes1: diamond structure space p 1 ! original space group: F d -3 m a = 3.5670 b = 3.5670 c = 3.5670 alpha = 90.0 beta = 90.0 gamma = 90.0 core = C1_1 edge = K rmax = 6.0 atoms ! elem x y z tag occ C 0.12500 0.12500 0.12500 C1_1 1 C 0.12500 0.62500 0.62500 C1_2 1 C 0.62500 0.12500 0.62500 C1_3 1 C 0.62500 0.62500 0.12500 C1_4 1 C 0.87500 0.37500 0.37500 C1_5 1 C 0.87500 0.87500 0.87500 C1_6 1 C 0.37500 0.37500 0.87500 C1_7 1 C 0.37500 0.87500 0.37500 C1_8 1 I also tried the Mercury demo, but all editing features are disabled. I will try Diamond now. Just to give some motivation here, I am working with abinit (along with feff) to produce optical spectra. If I use a conventional cell, the calculations become much more time consuming, so ideally I want to use a primitive cell. Thanks again for all your help! Josh
Hi Josh, You may try Diamond Demo version which is free.
http://www.crystalimpact.com/diamond/download.htm I will give this a try.
Hi Josh,
If I understand your question, I think that Atoms does what you want. Running the command line tool as "atoms -p" turns the attached cif file into the attached "p1.inp" file. You can do the same thing inside of Artemis using "write special output" in the Theory menu.
B
-- Bruce Ravel ----------------------------------- bravel@bnl.gov
National Institute of Standards and Technology Synchrotron Methods Group at Brookhaven National Laboratory Building 535A Upton NY, 11973
My homepage: http://cars9.uchicago.edu/~ravel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/
-----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov on behalf of joshua jason kas Sent: Wed 6/17/2009 2:16 PM To: ifeffit@millenia.cars.aps.anl.gov Subject: [Ifeffit] Primitive unit cell from .cif file
Hi everyone, I was wondering if there is a simple (free) utility for producing a primitive cell (not conventional) from an asymmetric cell and space group. Basically, I want to be able to easily go from a crystallographic information file to a primitive unit cell. I know that there are ways to do this within applications like material studio, but these are expensive. Any help would be appreciated. Thanks, Josh Kas _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit