# Determination of atomic bases in unit cell using Wien2k

1. ### hokhani

305
After specifying the primitive vectors of a structure namely (a,b,c) in Wien2k, one has to specify locations of atoms in unit cell.There are three components X,Y,Z which determine the atom location. I want to know whether "X,Y,Z components" are corresponding to vectors a,b,c or they are components of the cartesian system? In other words If we have a typical (X,Y,Z), dose it means that atom location is r=Xa/a+Yb/b+Zc/c or r=Xi/a+Yj/b+Zk/c?

2. ### Greg Bernhardt

I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?
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3. ### M Quack

847
I don't know Wien2k, but the usual convention is to specify XYZ in units of the unit cell vectors abc.

An easy way to check is to use a small, primitive low-symmetry cell, calculate whatever you calculate, and then to double a lattice parameter and add a basis e.g. at (1/2,0,0) for a-->2a. The result should be the same.

If not, you are not using the correct convention.

4. ### hokhani

305
Yes. you are right. I found that XYZ are in units of abc.