[Wien] Different results for LDA+U and GGA approximations in band structure calculation

[hossien rahnama]

Dear Wien2k users and Prof.Blaha, 
Thank you very much for your attentions. I am doing some calculations for transparent conductors (TCO materials). While I calculate band structure for TCO materials with two different approximations, LDA+U and GGA, I obtain two different curves for top of valance band in Gamma point. In the LDA+U approximation, curvature of valance band curve in Gamma point is up, and the GGA approximation, curvature of valance band curve in Gamma point is down. I want to know, which approximation is better and also give me good physical result?
  Furthermore, I have calculated band structure for TCO materials with Transition metal impurities (GGA approximation), I obtained different results. For some impurities curvature of valance band curve in Gamma point is up, and for the other impurities, curvature of valance band curve in Gamma point is down. I attention to, curvature of valance band curve in Gamma point is down, I want to know, my obtained results is correct or incorrect?
  Thanks a lot for any suggestion,
  Rahnama 
        
   


Hossein Asghar Rahnamaye Aliabad(PH.D Student)
Electroceramic and Material Laboratory
Department of Physics,Faculty of Science
Ferdowsi University of Mashhad, Iran
Phone:  +98 511 8644047
Web: www.um.ac.ir
Email: ho_ra71 at stu-mail.um.ac.ir, h_rahnamay at yahoo.com
       
---------------------------------
Need a vacation? Get great deals to amazing places on Yahoo! Travel. 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20070802/79725df1/attachment.html