[QE-users] Ensemble_DFT simulation

[Paolo Giannozzi]

I would say that the limiting factor is the Gamma-only (k=0) sampling 
used by CP. The larger the supercell, the better the sampling. For a 
sufficiently large supercell of Cu, or similar 3D systems, there should 
be no special problems with ensemble DFT.

Paolo

On 07/10/2022 07:19, KRISHNENDU MUKHERJEE wrote:
> 
> Thank you Paolo. I have just a small follow up question. Is ensemble_DFT suitable only for cluster inside vacuum in a box, or slab inside vacuum in a box?
> Or, with very careful choice of inputs we can apply ensemble_DFT for 3D cases too? For example; if I want to simulate a Cu supercell at 300 K?
> 
> Regards,
> Krishnendu
> 
> 
> ----- Original Message -----
> From: "paolo giannozzi" <paolo.giannozzi at uniud.it>
> To: users at lists.quantum-espresso.org, "KRISHNENDU MUKHERJEE" <krishnendu at nmlindia.org>
> Sent: Friday, October 7, 2022 2:14:38 AM
> Subject: Re: [QE-users] Ensemble_DFT simulation
> 
> Thank you for reporting this. Some examples have been run years ago and
> things have changed meanwhile
> 
> Paolo
> 
> On 06/10/2022 08:30, KRISHNENDU MUKHERJEE wrote:
>>
>> Dear Community,
>>
>> Few days back I wrote to this forum regarding the zero values of the
>> eigenvalues:
>>
>> --------------------------------------
>>
>> When I practised the example 08 given in CPV/examples, I got the note:
>>
>> NOTE : eigenvalues are not computed without ortho
>>
>> And the reported eigenvalues are all zeros.
>>
>> However, in the given reference output the note is not there. Also, the
>> eigen values are non-zero.
>>
>> Please suggest to solve the problem.
>>
>> ---------------------------------------
>>
>> To solve it, I think, one may do few steps of orthogonalization =
>> 'Gram-Schmidt', and then using the autopilot mode change it to
>> "orthogonalization = 'ortho'.
>>
>> By doing so, on_step 6, I got the values of the eigenvalues.
>>
>> In the reference example08, the eigenvalues at the end of step 5 were:
>>
>> Eigenvalues (eV), kp =1 , spin =1
>>
>> -9.73-8.12-3.55-2.45-2.45-1.20-1.200.82
>>
>> After Autopilot on_step 6, to orthogonalization = ‘ortho’, at the end of
>> 10 step the eigenvalues I got is:
>>
>> STEP:100.00
>>
>> Eigenvalues (eV), kp =1 , spin =1
>>
>> -9.75-8.13-3.56-2.46-2.46-1.21-1.210.93
>>
>> I hope in this way the cp.x runs with correct eigenvalues as compared to
>> what might be happening with orthogonalization = 'Gram-Schmidt',only.
>>
>> Thanking you,
>>
>> Regards,
>>
>> Krishnendu
>>
>>
>>
>>
>>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222