Hi all, So, great to know there are knowledgeable people on Vesta in the mailing list. My question is the following: I have a cubic structure, a perovskite. I have a [sqrt(2) x sqrt(2)] cell of this structure, with relaxed positions with rotated oxygen octahedra in the x-y plane only, out of which I would like to create a [2 x 2] cell. I actually managed to do it (using a xsf file that i created from the xyz output), but in a way which I would not call the most elegant. It is also a way that is more prone to errors, than I wish it were.
The problem is, when one loads an xsf file with the coordinates in Vesta, it displays a structure with more atoms than the unit cell actually does, and apparently it is the equivalent of XCrysDen's conventional cell mode. However, one can choose, in XCrysDen, to display only the translational asymmetric unit. This is one thing I don't know how to do in Vesta. For a matter of convenience (laziness, actually :) ), I have set both PRIMVEC and CONVVEC to the cubic lattice vectors, in the xsf file. Although I have managed to create a [2 x 2] cell, starting from the [sqrt(2) x sqrt(2)] using a transformation matrix (easy to deduce), I have to eliminate some atoms by setting boundaries to the fractional coordinates and checking that the number of atoms is actually the expected number. In the case of a [2 x 2] cell, of course, we have 4 times as many atoms as in the [1 x 1] cell. However, I would be more reassured if there were an automatic way to guarantee that the correct number of atoms would be output, instead of having to make somewhat extensive checks to ensure this. Another doubt is about symmetrization of atomic coordinates. If I choose a space group for Vesta to symmetrize the atoms' coordinates, it ends up creating extra atoms which I can't seem to eliminate - at least i don't know the correct way to do it. I have tried the option "remove duplicate atoms", but it didn't work. Has anyone run into such problems? If things are not clear, I'll be glad to provide an xsf file to illustrate the issues. Best regards, Marcos
