[Wien] Electric Field Gradient in case.scf_mini

[Peter Blaha]

I'm sorry, at the moment I cannot clarify what is ok and what is wrong:

The UG says it is a column vector; however, in the code (efg.f)  the
angle is calculated from a "row":
 
            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)
            WRITE(6,1355)   ((eivec(i,j),j=1,3),i=1,3),jatom,winkel

It could well be that "winkel" was programmed for a case where the EFG was
fixed along z and only x,y could rotate (in this case column or row does
not matter).

Please check it! (Take part of efg.f ; initialize   mat with "hand" selected 
values and diagonalize with    eigen3 and check the eigenvectors/angles.

I'd be gratefull if you could confirm which is right and which is wrong.

Regards
> 
> Dear Wien2k users,
> 
> I'm trying to calculate EFG and have some questions 
> concerning information about EFG in the case.scf_mini file. 
> A typical entry looks like below:
> 
>          MAIN DIRECTIONS OF THE EFG   1.0000  0.2760 -0.3709                 
>                                       0.4072 -0.5385  1.0000                 
>                                      -0.0567  1.0000  0.6408                 
> :ANG014:  ANGLE WITH OLD X-AXIS =        24.8                                
>                                                                              
> :ETA014:                         ASYMM. ETA =     0.56833
> 
> 
> I found in the usersguide that, this gives the eigenvectors of 
> EFG (in colums). If I'm not wrong this the axes of the "EFG cordinate 
> system".
> Thats why if the first column will be the x' axis (x axis in the 
> EFG system) the angle with the old x axis could be calculated as 
> follows:
> alpha = arccos(x . x'/|x|*|x'|). However when I take 
> x = (1,0,0) and x' = (1.000, 0.4072, -0.0567)
> I get alpha = 22.3 instead of 24.8. 
> 
> I've checked this for several results and I have never get
> exact angle shown in *.scf_mini. 
> 
> I will be appreciated if somebody could explain me how the angle 
> between the axes is calculated, or if there is an error in 
> my impretation.
> 
> Greetings
> Daniel Kmiec
> 
> -- 
> ______________________________________________________________________
> Mag. Daniel Kmiec             http://www.ap.univie.ac.at/users/kmiec/
> 
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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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