[QE-users] ?==?utf-8?q? Same run not accelerated when starting from converged rho and wfc

[Stefano de Gironcoli]

6.d-9 is still too large.. it should be something like 1d-13 to aim at a 
smaller scf estimate.

are you really starting from the scf charge and wfcs of the same 
conficuration ?

stefano

On 16/08/20 22:05, Antoine Jay wrote:
> Dear Stephano,
> adding diago_thr_int=1.0D-8 does not change the first conv_thr (exept 
> the average#of iterations)
> As you said, the first value 1.0D-2 is detected to  be too large and 
> is updated to 6.0D-9 so I don't see why changing manually the first 
> value would change something if it is already automatically changed...
>
> Antoine Jay
> LAAS-CNRS
> Toulouse, France
>
> Le Samedi, Août 15, 2020 17:10 CEST, Stefano de Gironcoli 
> <degironc at sissa.it> a écrit:
>
> Hi Antoine,
>
>   don't know exactly why you get this result but one thing you can try 
> is to set diag_thr_init ~ conv_thr/Nelec/10 so the first 
> diagonalization is pushed tighter (if the wfcs are already very good 
> it should not take too many iterations) and the computed dr2 estimate 
> should be more faithful
>
>   now diag_thr_int is 1.d-2 then updated to 6.e-9 which is consistent 
> with conv_thr ~6.d-5...
>
>   idk. you can try
>
>   stefano
>
> On 14/08/20 17:09, Antoine Jay wrote:
>> Dear all,
>>
>> I'am doing two consecutive scf calculations with exactly the same 
>> structure and parameters by calling qe6.5 as a library (attached 
>> output files).
>> For the second call, I use the options:
>> startingwfc='file' and input_rho ='rho.in'
>> where these inputs are the converged wfc1.dat and charge-density.dat 
>> of the first step.
>> Here I face two problems:
>>
>> -I expected that the initial scf accuracy is 10^-11 as obtained at 
>> the end of the first step, but it is only 10^-4.
>> How is it possible to explain such a decrease? I generally loose only 
>> 2 orders of magnitude by doing this.
>>
>> -Even with less scf iterations, the cpu time is greater.
>> Is it possible that some extra memory is allocated by qe when input 
>> rho and wfc are asked, and not desallocated?
>>
>> Note that until now, I have these troubles only when I use paw 
>> pseudopotentials on big systems.
>>
>> Regards,
>>
>> Antoine Jay
>> LAAS-CNRS
>> Toulouse France
>>
>>
>>
>>
>>
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>
>
>
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