[Wien] q re: 'local coordinates' and px, py, pz

[Cormac McGuinness]

Dear Wien users,

I am calculating a system where O atoms are on sites with point-group m
(C_s) bonding in a plane with 1 Cu and 2 Ti atoms. My question is what
are the 'local coordinates' i.e. in which directions are p_x p_y and p_z
oriented (this being the way that WIEN2k splits the p-states)

>From the discussion in the archives of Oct 2003 with the subject "how to
calculate the DOS of p(sigma) or p(pi)":

> P.Blaha wrote in response to Yushan Wang:
>
> a) WIEN usually selects the proper coordinate system for you (i.e. it
> introduces automatically a "local coordinate system" if necessary for
> "proper" analysis).
> A simple example of what is going on: Suppose you do a diatomic 
> molecule with coordinates (0,0,0) and (x,x,0). In this case WIEN will
> introduce "local coordinates" and put the z axis along the (1,1,0)
> direction. Thus you will get an eigenvalue (orbital) which has p-z
> character (that's your sigma orbital), and other eigenvalues with
> px,py character (these are the pi orbitals in this case).
> Without the local coordinates the px orbital would be part of both,
> the sigma AND the pi orbitals.
>

Is x oriented towards the Cu atom, y in the plane of the atoms and z out
of the plane ? or is z directed towards the Cu atom ?

I should note that WIEN2k does not suggest a local rotation matrix but
does give in case.outputsgroup the following information

Sort number: 4
  Names of point group: m      m      Cs
  New basis vectors for this point group:
    1.0000   0.0000  0.0000  <--- 1
   -1.0000   0.0000 -1.0000  <--- 2
    0.0000   1.0000  0.0000  <--- 3

Perhaps I could also ask for an interpretation of the above ?

Yours gratefully
Cormac
-- 
Dr. Cormac McGuinness, Lecturer, Physics Dept. Trinity College,
Dublin 2, Ireland.