[Wien] Direction of EFG

[Peter Blaha]

It's along time since this was programmed and most likely the "angle" 
stems from a time where I had only an EFG tensor with xy-crossterm, but no 
xz,yz. Thus the EFG is rotated only within the xy-plane and the 
angle is the angle with the original x-axis.
Anyway, if I remember correctly, 
the "matrix of eigenvectors" should be read column wise (not row wise).



> I am interested in the angles between the hyperfine field and the electric 
> field gradient. According to the code (efg.f in the SRC_lapw0), the matrix 
> denoted in output0 as MAIN DIRECTIONS OF THE EFG gives columns which are the 
> eigen vectors of EFG. But what is   ANGLE WITH OLD X-AXIS ?
> In the text of program it is 
>             anorm=sqrt(eivec(1,1)**2+eivec(1,2)**2+eivec(1,3)**2)
>             winkel=acos(eivec(1,1)/anorm) * 180.d0 / acos(-1.d0)
> So, it looks like the angle between X in the local system of atom and some 
> vector made of first row of the matrix, that is, first components of eigen 
> vectors eivec(1,1), eivec(1,2), eivec(1,3). What is it? Shouldn't it be
>             anorm=sqrt(eivec(1,1)**2+eivec(2,1)**2+eivec(3,1)**2)
> Though there is no some special significance in this angle, also; but 
> nevertheless, this is a real angle. Or I misunderstand something?
> 
> Best regards
>   Lyudmila Dobysheva             
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                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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