#6 universal scaling factor in VASP POSCAR generated file

[Anonymous]

Hi, I use cif2cell which actually works fine. I have one question about the way cif2cell builts vasp POSCAR: does the universal scaling factor obtained only apply on lattice parameters or do I need to apply it to the coordinates too? Many thanks for your help.

François

[Anonymous]

I'm not quite sure I understand the question. CIF2Cell will by default set up the POSCAR so that the scaling factor is equal to the 'a' lattice parameter and the lattice vectors is then given in units of 'a'. The coordinates are by default given as what VASP calls 'Direct' coordinates, which is to say that they are in units of the lattice vectors, so no need to rescale anything.

In case you want to see the actual cartesian coordinates, you give CIF2cell the flag --vasp-cartesian-positions it will instead be in 'Cartesian' coordinates, x, y, z in ångström. You have also the flag --vasp-cartesian-lattice-vectors, which sets the scaling factor to 1 and has the lattice vectors in ångström. The flag --vasp-cartesian applies both of these.

You can do this any way you like, they all give POSCAR files ready to use in VASP with the same structure, just differing a little in how they look. One of the ideas with CIF2Cell is that it relieves the user from having to fiddle around with the POSCAR file, or even know and understand the format, you just need your CIF.

Hope this helps.
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