[CP2K-user] OT produces negative gap for 1eV gapped semiconductor?

Nicholas Winner nwi... at berkeley.edu
Wed Jun 2 19:25:40 UTC 2021

Hello everyone. I have a semiconductor, BeSiP2, which has a band gap 
slightly above 1eV in the GGA approximation 

I calculate a vacancy, V_{P}^{+3}, first using diagonalization. Which 
produces a band gap around 1eV, indicating that the charge does not 
delocalize, and so OT should still be appropriate. When I switch to OT, 
however, there is a negative homo/lumo gap and I can see it in the 

0.17131297      0.17154145      0.18362819      0.18519005

 Fermi Energy [eV] :    5.039278

  Lowest Eigenvalues of the unoccupied subspace spin            1


  Reached convergence in            1  iterations

       0.18499549      0.22295666      0.23850766      0.25228060

This is bizarre to me. OT is usually very reliable for me. So this is a 
strange inconsistency, and maybe its due to how I'm running the 
calculation. For OT I use the full_all preconditioner, and the rest 
defaults. For diagonalization I the section at the bottom. Anyone have any 
guesses as to why there is this discrepancy? 



    MAX_SCF 200

    added_mos 100

    eps_scf 1e-6

    max_diis 15






        elec_temp 300

        method fermi_dirac 


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20210602/b20ac00c/attachment.htm>

More information about the CP2K-user mailing list