Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Robert, It seems you are sort of cherry picking through the code. When I first wrote Xray::Crystal, I spent a lot of time pouring over chapter 5 of ITC volume A. I am mostly confident that the various transformations are applied correctly in response to space group symbol choices. Demeter

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Hi Bruce, I looked at Site.pm and Cell.pm as well (and I don't program in perl, so please forgive any naivete). In Site.pm, lines 188 - 191, it says: #-- rotate from F or C settings to P or I if ($is_tetr) { ($x, $y) = ($x-$y, $x+$y); }; and this looks like a

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

On 12/21/2016 02:50 PM, Robert Gordon wrote: So, for all but tetragonal, the orientation of the cluster can be identified with the orientation of the crystal axes. Does it not seem more logical to preserve the apparent orientation with respect to the crystal axes so that, when using POLARIZATION

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Hi Bruce, Sorry, I was just using the different space group just to get the cluster to be oriented along the axes or at 45 degrees. With tetragonal symmetry, the cluster is oriented at 45 degrees with respect to the axes. If I don't use tetragonal symmetry, then the cluster is oriented as

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Robert, On Wed, Dec 21, 2016 at 12:13 PM, Robert Gordon wrote: > > Hi Bruce, > > The atoms.inp file attached is for bct Fe. In symmetry I4/mmm, the > resulting feff input has the coordinates > rotated, while in Immm the resulting coordinates are not rotated relative >

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Robert, You have me confused. You seem to be saying that using the correct space group symbol is important. I couldn't possibly disagree. Raj's original question had to do with the fact that two different versions of atoms, which used different algorithms for interpreting the crystal

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Hi Bruce, The atoms.inp file attached is for bct Fe. In symmetry I4/mmm, the resulting feff input has the coordinates rotated, while in Immm the resulting coordinates are not rotated relative to the crystal axes (i.e. in Immm the 2nd near neighbour is obvious as a lattice constant away in each

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

On 12/19/2016 11:01 PM, Robert Gordon wrote: What if one were to do this FEFF calculation using the POLARIZATION card? 1 0 0 means something different if the atom positions have been rotated by 45 degrees relative to the crystal axes along which the polarization is defined. Well ... you could

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Hi Bruce, What if one were to do this FEFF calculation using the POLARIZATION card? 1 0 0 means something different if the atom positions have been rotated by 45 degrees relative to the crystal axes along which the polarization is defined. -R. On 12/16/2016 10:14 AM, Bruce Ravel wrote: On

Re: [Ifeffit] Ifeffit Digest, Vol 166, Issue 12

Hi Bruce, Thanks for the explanation. Yes, both files are generating the same kind of output but the positioning of atoms can mislead in the context of structure. That's why i have raised the question. Regards, Raj On 16 December 2016 at 16:48, wrote: