[Wien] a question about the atomic coordinates in file of case.outputs

[Zhou Bing]

Dear all,

I try to understand how the atomic coordinates in crystallographic system are transformed into the orthogonal system by WIEN2k.  

I am wondering if  the atomic coordinates are transformed by WIEN2k using the following equations:

In the general case with angles that can be different from 90 degrees:
- the a-axis is depicted on the x-axis.
- The b-axis lies in the xy-plane (with the angle gamma between the a- and b-axis).
- The c-axis points towards you.
 
So x-coordinate is easy to calculate, the z-coordinate is complicated!
 
Here in total: (x1,y,1,z1) is crystal coordinates, (x2,y2,z2) is orthogonal coordinates.
 
x2 = x1 * a
 
y2 = x1 * b * cos(gamma) + y1 * b * sin(gamma)  [when gamma == 90 deg -> y2 = y1 * b]
 
z2 = x1 * c * cos(beta) + y1 * c * P + z1 * c * Q
 
with: P = (cos(alpha) - cos(beta) * cos(gamma)) / sin(gamma)
and: Q = sqrt(sin^2(beta) - P^2)

Thank you in advance!

Best wishes,

Bing



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