I don't know if your method is correct, since I don't know your method. But: > > I want to dope an element Y into the inverse spinel structure AB2O4. It > has spacegroup 227 Fd-3m. However, Wien2k led me to use spacegroup 74 Imma > with B lattice for this > > structure, because it requires use of non-equivalent atoms.
Already this statement makes me suspicious. You have to use SG 227 ! But remember: there are 2 different "settings" of this SG and you have to enter the positions compatible with the setting with inversion symmetry. Study the spacegroups (see the link to the Bilbao-server) I suggest you start out with elemental Si and try to setup this structure correctly. Once you have your spinel with SG 227, you run supercell. You have to think how large your supercell should be (how many atoms you want to have). Typical values range from 32 to 128 !!! So if your original F-centered cell has 7 atoms (or 14 ? I can't remember exactly ...) you can run supercell: 1x1x1, P-lattice. This gives 4x7 =28 atoms (which is very small). Then you would eventually split a position and introduce the dopant. 2x2x2, F-lattice: 8+7=56 atoms is a bit better 2x2x2, B-lattice: 16x7 atoms, pretty good ... 2x2x2, P-lattice: 32x7=224 atoms: very good... If your original cell has more atoms (14) the procedure is very similar, but of course you would stop earlier. Am 09.01.2013 23:11, schrieb Mohamed ouaissa: > Dear Peter, > > Thanks, but can you tell me if my method to dope a structure is correct? > > In other words, I have 74 Imma with B lattice, so select B lattice in > StructGen to split positions and add atoms, then use sgroup to find the new > structure (12 C2/m). > > Is it possible to tell me what i should do exactely? > > Thanks in advance for your response. > > Mohamed > > > ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- > *De :* Peter Blaha <pblaha at theochem.tuwien.ac.at> > *? :* A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at> > *Envoy? le :* Mercredi 9 janvier 2013 7h16 > *Objet :* Re: [Wien] supercell > > At www.wien2k.at you can find the lecture note of our workshop at pennstate > (http://www.wien2k.at/) > > Checkout my "getting started" document and maybe you can then understand the > meaning of P,B or F > in supercell. > > Am 09.01.2013 00:27, schrieb Mohamed ouaissa: > > Dear wien2k users, > > > > I want to dope an element Y into the inverse spinel structure AB2O4. It > has spacegroup 227 Fd-3m. However, Wien2k led me to use spacegroup 74 Imma > with B lattice for this > > structure, because it requires use of non-equivalent atoms. To dope > element Y in place of element A, for example A1-xYxB2O4 with different values > of x , I use supercell > > input 1, 1, and 1 for number of cells in x, y, and z direction, and shift > of atoms (0, 0, 0). Since my the starting lattice is B, so I used a target > lattice of B. Then, I > > split element A having one non-equivalent position into two non-equivalent > positions (for element A and Y) using StructGen. Finally, after running > sgroup, it gives me a > > structure with spacegroup 12 C2/m having CXZ lattice. Does someone know > if this is the correct procedure? Is it correct to use B as the target > lattice, or should the P > > lattice be used to split the 4e site for spacegroup 51 Pmma having P > lattice? > > > > What about if i will use a supercell 2, 1, and 1 or 2, 2, and 1 or 2, 2, > and 2 ?? > > > > Thanks in advance for your response. > > > > Mohamed Ouaissa > > > > > > > > > > _______________________________________________ > > Wien mailing list > > Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at > zeus.theochem.tuwien.ac.at> > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > > -- > ----------------------------------------- > Peter Blaha > Inst. Materials Chemistry, TU Vienna > Getreidemarkt 9, A-1060 Vienna, Austria > Tel: +43-1-5880115671 > Fax: +43-1-5880115698 > email: pblaha at theochem.tuwien.ac.at <mailto:pblaha at > theochem.tuwien.ac.at> > ----------------------------------------- > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at zeus.theochem.tuwien.ac.at> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > -- ----------------------------------------- Peter Blaha Inst. Materials Chemistry, TU Vienna Getreidemarkt 9, A-1060 Vienna, Austria Tel: +43-1-5880115671 Fax: +43-1-5880115698 email: pblaha at theochem.tuwien.ac.at -----------------------------------------
