[Wien] ghost band

[Yeoh Yen Fun]

Dear Stefaan,

Thank you very much for your prompt reply and advice.
I have restarted the initialization from a scratch directory. The SCF 
iteration stopped at cycle 9 after lapw1. Again, all the error files 
were empty. The case.scf2 file shown message: QTL-B value EQ 5.59310 in 
band of energy  -0.55906 atom = 12, L=1. The fermi level was 0.10020
I tried to remove the broyden file, changed all global E-parameter from 
-0.04 to -0.10, and changed E-parameter for atom 12, L=1 from 0.3 to 
-0.5 in case.in1c file. The SCF iteration then was stopped at cycle 20 
with the message "Forces not converged". The ghost band message still 
exist but apparently, the value was reduced to 3.246 for atom 2.
I tried to decrease the mixing factor in case.inm file from 0.01 to 
0.005 and restarted the SCF iteration. But the same problem occurred, 
where the iteration stop at cycle 20 with message "Forces not 
converged". (The issued command was: run_lapw -p -fc 1 NI)
I don't have experience to solve the scf converged problem. Any 
suggestion? Should I ignore the ghost band message since the qtl value 
was quite small?

Thanks in advance

Regards
Yen Fun


Stefaan Cottenier wrote:
>> , I don’t understand why LO is added in case.in1 file (in what case we 
>> should add the LO), and how to define the energy for this LO. Can 
>> anyone explain to me?
>>     
>
> Most of the LO's are decided upon automatically, and this is fairly 
> robust. What you probably refer to is adding extra LO's at high 
> energies. This is needed when you are interested in the DOS of 
> unoccupied states. This enhances precision, but is rarely necessary to 
> get a case converged. I don't think your troubles are due to this.
>
>   
>> Currently I tried to run an interface LiTaO3/RuO2. Everything was fine 
>> during initialization. When come to scf calculation, the dayfile 
>> message shown: /INFO: K-LIST in CLMSUM changed in MIXER xxx /after 
>> Lapw1,and QTL-B value shown after Lapw2.The calculation was then stop 
>> with message “lapw2 crashed!” at cycle 2. In this case I used RmtKmax 
>> 5 with Kmesh 50. I understand that we can ignore the K-list message in 
>> cycle 1. So I presume that the ghostband have caused the problem 
>> (QTL-B value >5%). Thus, I tried to change all E-parameter from 0.3 Ry 
>> to -0.04 Ry, which is 0.2 Ry below the Fermi Level and rerun the scf. 
>> But it doesn’t help. The same error occurred again.
>>     
>
> Re-initialize from scratch in a new, clean directory to make sure that 
> this k-list message is really there. It could be a result of messing up 
> something while playing with the initialization. If it still crashes 
> after lapw2, look at the bottom of case.scf2 to see which state triggers 
> the qtl-b problem. You will also see there to what value you have the 
> change the linearization energy of that state.
>
>   
>> I tried to switch “in1new 5”, but this time the calculation even stop 
>> at 1^st cycle. Then I tried to reduce the mixing factor from 0.1 to 
>> 0.01, with restart the dstart. The calculation then stopped at cycle 4 
>> after LAPW1, with empty error file.
>>     
>
> I assume you are making all these changes in the same directory? If you 
> do not know exactly what you are doing, it's easy to mess things up. For 
> such a big interface supercell, I would definitely start with a mixing 
> value around 0.01. Try it, in a clean directory. If there is really no 
> error message, look in case.dayfile and to your 'screen' output to find 
> out why it stopped (queue problem?)
>
>   
>> Another thing I want to note here is I found that there is no core for 
>> Lithium, where from case.scfc file, I noticed that the core for 
>> Lithium is 0.0000Ry. I am not sure whether this is the cause for the 
>> problem or not. Did anyone face the same problem before?
>>     
>
> That is no problem. The 1s level of Li is at -3.8 Ry, the 2s is at -0.2 
> Ry. With the default separation energy of -6 Ry, both fall in the 
> valence region. There are no core states for Li.
>
> Stefaan
>
>
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