[Wien] about famous QTL-B and ghostband problem

[Hongjun Xiang]

Dear Prof. Blaha,
I got it and thank you very much for the clarification.

Best regards,
Hongjun Xiang


Peter Blaha wrote:
> Your scf results are ok, because all occupied states are ok.
> For the DOS, however, also unoccupied states are calculated and it was 
> found that at high energy (2.3 Ry) some ghostbands appear.
>
> You can ignore it if not interested in high DOS or:
> 2 ways of fixing: either reduce the EMAX in case.in1, so that these high 
> eigenvalues are not written, or, better, adjust (increase) the E-parameter 
> for atom=2 l=1 to a larger value (maybe 1.5 Ry as first guess)
>
>   
>>    I am using spin orbit and LDA+U to calculate a system with Na+ ions.
>> The scf finished normally without any such message like
>> "Check for ghostbands or EIGENVALUES BELOW XX messages" in 
>> case.output2up/dn file.
>> However, when I calculate the DOS using:
>> x lapw2 -qtl -up -so
>> x lapw2 -qtl -dn -so
>>
>> I found in case.output2up file: 
>>   QTL-B VALUE .EQ.   34.42258   in Band of energy    2.31653   ATOM=    
>> 2   L=  1
>>     Check for ghostbands or EIGENVALUES BELOW XX messages
>>     Adjust your Energy-parameters or use -in1new switch, check RMTs  !!!
>>
>> My .in1 file for Na looks like:
>> WFFIL        (WFPRI, SUPWF)
>>   7.00       10    4 (R-MT*K-MAX; MAX L IN WF, V-NMT
>>   ...
>>  0.30    4  0      (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global 
>> APW/LAPW)
>>  0    0.30      0.000 CONT 1
>>  0   -3.86      0.005 STOP 1
>>  1   -1.80      0.010 CONT 1
>>  1    0.30      0.000 CONT 1
>>   ...
>> K-VECTORS FROM UNIT:4   -7.8       2.5      emin/emax window
>>
>> The fermi energy is  0.56930 Ry.
>> Apparently, the ghostband (if it is) is located in very high energy and is
>> related to the LO orbital for Na p orbital  with energy parameter  0.30.
>> My questions are:
>> Is my scf result correct?
>> Should I  change 0.30 to some other high value (such as 1.3 Ry) and 
>> restart scf?
>> Is this unoccupied LO for Na p orbital necessary?
>> Or can I ignore this since I am not interested in the DOS with energy 
>> higher than 2 Ry?
>>
>> Thank you very much.
>>
>> Best regards,
>> Hongjun Xiang
>>
>>
>>
>>     

>>                                       P.Blaha
>> --------------------------------------------------------------------------
>> 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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