RE: mismatch between ICSD cif file and GSAS
Title: Message Don, As Allen Larson noted GSAS only uses the 2nd setting for space groups that have two (e.g. F d 3 m) so that he inversion center is placed at the origin. The eta alumina structure you have is for the 1st setting. To convert from 1st to 2nd subtract 1/8,1/8,1/8 from all xyz. That will fix the structure factors & the site multiplicity problems. Bob Von Dreele R.B. Von Dreele IPNS Division Argonne National Laboratory Argonne, IL 60439-4814 -Original Message-From: Donald Wang [mailto:[EMAIL PROTECTED] Sent: Sunday, May 15, 2005 9:31 PMTo: rietveld_l@ill.frSubject: mismatch between ICSD cif file and GSAS Dear all, I have a puzzle here. I have been learning GSAS for a while but still at a relatively low level. I am trying to calculate % of glass phase in a plasma sprayed alumina coating (eta alumina, ISCD #39104, space group Fd-3M, 227). The structure is copy-pasted as below: Atom # OX SITE x y z SOF H ITF(B) O 1 -2 32 e 0.37 0.37 0.37 1. 0 3. Al 1 +3 8 a 0.25 0.25 0.25 0.503 0 3. Al 2 +3 48 f 0.25 0 0 0.083 0 3. Al 3 +3 16 d 0.625 0.625 0.625 0.564 0 3. Al 4 +3 16 c 0.125 0.125 0.125 0.27 0 3. However, when this CIF file is imported into GSAS (using EXPGUI), EXPGUI shows the following corresponding multiplicity 32 32 32 8 8 and GSAS-simulated XRD pattern is much different from the one generated from ICSD. Please help on this mismatch between ICSD and GSAS-EXPGUI. Many thanks in advance Don Donald Wang University of Connecticut
mismatch between ICSD cif file and GSAS
Title: Message Drs. Payzant, Larson, & Von Dreele, Thanks for your quick response. After 1/8 offset, it appears that the pattern from live plot is a good match to ICSD-generated pattern, which basically solved my problem. I am very happy and grateful. There is still a little problem. The multiplicity column did not change at all (in EXPGUI). Please explain. Best regards Don -Original Message- From: Von Dreele, Robert B. [mailto:[EMAIL PROTECTED] Sent: Monday, May 16, 2005 9:30 AM To: rietveld_l@ill.fr Subject: RE: mismatch between ICSD cif file and GSAS Don, As Allen Larson noted GSAS only uses the 2nd setting for space groups that have two (e.g. F d 3 m) so that he inversion center is placed at the origin. The eta alumina structure you have is for the 1st setting. To convert from 1st to 2nd subtract 1/8,1/8,1/8 from all xyz. That will fix the structure factors & the site multiplicity problems. Bob Von Dreele R.B. Von Dreele IPNS Division Argonne National Laboratory Argonne, IL 60439-4814 -Original Message- From: Donald Wang [mailto:[EMAIL PROTECTED] Sent: Sunday, May 15, 2005 9:31 PM To: rietveld_l@ill.fr Subject: mismatch between ICSD cif file and GSAS Dear all, I have a puzzle here. I have been learning GSAS for a while but still at a relatively low level. I am trying to calculate % of glass phase in a plasma sprayed alumina coating (eta alumina, ISCD #39104, space group Fd-3M, 227). The structure is copy-pasted as below: Atom # OX SITE x y z SOF H ITF(B) O 1 -2 32 e 0.37 0.37 0.37 1. 0 3. Al 1 +3 8 a 0.25 0.25 0.25 0.503 0 3. Al 2 +3 48 f 0.25 0 0 0.083 0 3. Al 3 +3 16 d 0.625 0.625 0.625 0.564 0 3. Al 4 +3 16 c 0.125 0.125 0.125 0.27 0 3. However, when this CIF file is imported into GSAS (using EXPGUI), EXPGUI shows the following corresponding multiplicity 32 32 32 8 8 and GSAS-simulated XRD pattern is much different from the one generated from ICSD. Please help on this mismatch between ICSD and GSAS-EXPGUI. Many thanks in advance Don Donald Wang University of Connecticut
R: mismatch between ICSD cif file and GSAS
Title: Message Dear Don, I observed too that in Expgui multiplicity column is not always readily updated when one changes position/multiplicity. To have an update also in Expgui I usually run Expedt (GSAS interface) then I go to the "list atom menu" (i.e. sequence L A L), where I can see the true and updated list of multiplicities; after if I exit GSAS and come back to Expgui I see the updated list of multiplicities. Good job, Marco - Original Message - From: Donald Wang To: rietveld_l@ill.fr Sent: Tuesday, May 17, 2005 6:31 AM Subject: mismatch between ICSD cif file and GSAS Drs. Payzant, Larson, & Von Dreele, Thanks for your quick response. After 1/8 offset, it appears that the pattern from live plot is a good match to ICSD-generated pattern, which basically solved my problem. I am very happy and grateful. There is still a little problem. The multiplicity column did not change at all (in EXPGUI). Please explain. Best regards Don -Original Message-From: Von Dreele, Robert B. [mailto:[EMAIL PROTECTED] Sent: Monday, May 16, 2005 9:30 AMTo: rietveld_l@ill.frSubject: RE: mismatch between ICSD cif file and GSAS Don, As Allen Larson noted GSAS only uses the 2nd setting for space groups that have two (e.g. F d 3 m) so that he inversion center is placed at the origin. The eta alumina structure you have is for the 1st setting. To convert from 1st to 2nd subtract 1/8,1/8,1/8 from all xyz. That will fix the structure factors & the site multiplicity problems. Bob Von Dreele R.B. Von Dreele IPNS Division Argonne National Laboratory Argonne, IL 60439-4814 -Original Message-From: Donald Wang [mailto:[EMAIL PROTECTED] Sent: Sunday, May 15, 2005 9:31 PMTo: rietveld_l@ill.frSubject: mismatch between ICSD cif file and GSAS Dear all, I have a puzzle here. I have been learning GSAS for a while but still at a relatively low level. I am trying to calculate % of glass phase in a plasma sprayed alumina coating (eta alumina, ISCD #39104, space group Fd-3M, 227). The structure is copy-pasted as below: Atom # OX SITE x y z SOF H ITF(B) O 1 -2 32 e 0.37 0.37 0.37 1. 0 3. Al 1 +3 8 a 0.25 0.25 0.25 0.503 0 3. Al 2 +3 48 f 0.25 0 0 0.083 0 3. Al 3 +3 16 d 0.625 0.625 0.625 0.564 0 3. Al 4 +3 16 c 0.125 0.125 0.125 0.27 0 3. However, when this CIF file is imported into GSAS (using EXPGUI), EXPGUI shows the following corresponding multiplicity 32 32 32 8 8 and GSAS-simulated XRD pattern is much different from the one generated from ICSD. Please help on this mismatch between ICSD and GSAS-EXPGUI. Many thanks in advance Don Donald Wang University of Connecticut
