[Wien] LSDA+U

[Ricardo Faccio]

Hi
another possibility is to perform a constraint LDA calculations to extract de U value
Please see:
http://www.wien2k.at/reg_user/textbooks/Constraint_U.pdf
by G. Madsen and P. Novak.
Regards
Ricardo
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-----   Ing. Quím. Ricardo Faccio
 
  Mail: Cryssmat-Lab., Cátedra de Física, DETEMA
  Facultad de Química, Universidad de la República
       Av. Gral. Flores 2124, C.C. 1157
       C.P. 11800, Montevideo, Uruguay.
  E-mail: rfaccio at fq.edu.uy
  Phone: 598 2 9241860 Int. 109
             598 2 9290705
  Fax:    598 2 9241906
  Web:  http://cryssmat.fq.edu.uy/ricardo/ricardo.htm
  ----- Original Message ----- 
  From: Igor Djerdj 
  To: wien at zeus.theochem.tuwien.ac.at 
  Sent: Tuesday, July 10, 2007 12:00 PM
  Subject: [Wien] LSDA+U


  Dear all,
  Few months ago I submitted the post here regarding the calculation of electronic structure of VOxHy compound. I followed advices which I got here related to chooice of RMTs, RKmax, etc.. and ended with compound which shows metallic behavior. According to DC conductivity measurement the investigated compound is semiconducting with bang gap of around 0.64 eV. Then I tried DFT calculation using LSDA+U approach, and obtained this time Fermi level just slightly below the top of valence band and the width of band gap strongly dependent of the value of U. For instance for U=0.6 eV Eg=2.1 eV, U=4 eV, Eg=0.7 eV. The question is about reliability of the applied method i.e. which value of U is recommendable for 3d electrons of V? There are also changes in DOS with the change of U.
  Regards,
  Igor



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