[Wien] Reference energy for eigenvalues

[Oleg Rubel]

Dear Wien2k Community,

I need to compare eigenvalues calculated with Wien2k for different  
compounds. I found a number of discussions in the mail-list regarding  
the issue of the reference energy. They all concur that the reference  
energy is an average potential in the interstitial region. In one of  
the postings  
(http://zeus.theochem.tuwien.ac.at/pipermail/wien/2004-September/003582.html)  
Peter Blaha suggests UST0 returned by
CALL REAN3(NKK,KZZ,CVALUE,IFF1,IFF2,IFF3,CFFT,UST,UST0)
be the value of the potential in the interstitial region (if I  
understand it correctly).

I wander what are the units of UST0? It seems that UST0 is  
proportional to the volume of the unit cell. In GaAs I found:
UST0 = 231.58 (UNIT CELL VOLUME =     298.59750)
UST0 = 926.31 (UNIT CELL VOLUME =    1194.38998)
corresponding to 2-atom and 8-atom basis. Obviously, in case of the  
average potential, it should not change at all for the same compound.  
Nevertheless, eigenvalues of 3d electrons are -2.30 and -0.73 Ry in  
both cases.

An isolated "As" has the eigenvalue of 3d electrons at -2.95 Ry. I  
would expect the difference between -2.30 and -2.95 Ry to be mainly  
due to the change of the reference energy. But how to bring  
eigenvalues to the same scale?

Please help!

Thank you in advance,

Oleg Rubel

-- 
Oleg Rubel, Ph.D.
Thunder Bay Regional Research Institute
290 Munro St
Thunder Bay, Ontario
P7A 7T1, CANADA
E-mail: Oleg.Rubel at physik.uni-marburg.de
Homepage: http://www.staff.uni-marburg.de/~rubel/