Fractional occupancies are not possible. If you want to simulate substitutions or vacancies, you need to start with the unsubstituted structure. In case the cell is already large enough, you may just break symmetry (remove the spacegroup and use just the lattice type) and replace some of the atoms by others, otherwise use supercell to create a larger cell and introduce your substitutions (or remove atoms for vacancies).
supercell can be used through w2web (single program). Alexios P. Douvalis schrieb: > Hi all > Can someone give me some suggestion on how to insert in the . struct > file different occupancies of the same crystallographic site by a number > of different kinds of atoms (e.g. substitution cases like Fe2-xCrxO3, > Fe3-xZnxO4 etc...). Do I have to use the supercell program? Can this be > done through the w2web interface? I couldn't find something related to > this issue on the 'StructGen' interface. Do I have to edit the .struct > file? What about vacancies (occupancy <1)? > > Thanks in advance > > A.P. Douvalis > -- ----------------------------------------- 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 -----------------------------------------
