[Pw_forum] "scf" calculation with "PBE0" hybrid functional

[dario rocca]

I will let the MD experts to reply to this question :)

On Sat, Aug 6, 2016 at 2:49 AM, Narendranath Ghosh <ghosh.naren13 at gmail.com>
wrote:

> Dear Dario
>
> Thank you very much for your valuable suggestion. As my systems are quite
> large and require high computational resources , I decided to compare one
> of my result with that of PBE0.
>
> One problem that I am facing now "after successfully optimized the
> (CNT+Fullerene) systems now I am looking for  to get 5 picosecond "md"
> trajectory".
> In QE which flags  allowed one to get *MD trajectories * *with NVE
> ensemble. *I find some idea from http://qe-forge.org/piper
> mail/pw_forum/2009-June/087573.html. But that is not clear to me.
>
> Please suggest any idea.....
>
> Thank you again
>
> *Narendra Nath Ghosh*
>
> *Research Associate*
>
> *University of Gour Banga*
>
> *Department of Computational Physics *
>
> *Malda-732102*
>
> *India*
>
> On Sat, Aug 6, 2016 at 10:48 AM, dario rocca <roccad at gmail.com> wrote:
>
>> Dear Narendra,
>> If you do a PBE calculation with norm-conserving, ultrasoft, and PAW
>> pseudopotentials very likely you will get very similar results (but it
>> depends
>> also on the quality of the pseudopotential, the property under
>> consideration, etc.).
>> In the case of PBE0 the type of pseudopotential will have a stronger
>> effect on the final result.
>> For purely esthetic reasons, if your previous calculations didn't take
>> too long you could redo them with norm-conserving pseudopotentials and
>> confirm that the results are indeed the same.
>> Otherwise I don't see anything wrong in comparing, for example, a gap
>> obtained at PBE level with US pseudos and a gap obtained at PBE0
>> level with NC pseudos.
>> Best,
>> Dario
>>
>>
>>
>> On Fri, Aug 5, 2016 at 3:44 PM, Narendranath Ghosh <
>> ghosh.naren13 at gmail.com> wrote:
>>
>>> Dear Dario
>>>
>>> Thank you very much  for your support.It works well and some of the
>>> jobs have been finished successfully.
>>>
>>> But one thing in my mind. In my whole calculations , I used PBE with
>>> ultrasoft pseudopotentials. But to do "scf" calculations with  PBE0 "hybrid"
>>> functional I have to use "Norm conserving pseudopotential". So how can
>>> I compare these two results.
>>>
>>> Please suggest any idea.....
>>>
>>> Thank you again
>>>
>>> *Narendra Nath Ghosh*
>>>
>>> *Research Associate*
>>>
>>> *University of Gour Banga*
>>>
>>> *Department of Computational Physics *
>>>
>>> *Malda-732102*
>>>
>>> *India*
>>>
>>>
>>> On Thu, Aug 4, 2016 at 2:17 AM, dario rocca <roccad at gmail.com> wrote:
>>>
>>>> Dear Narendranath,
>>>> Your calculation has reached convergence if you read the message "EXX
>>>> self-consistency reached".
>>>> You can learn some details about the scf procedure with hybrid
>>>> functionals in PW/examples/EXX_example.
>>>> PBE0 and hybrid functional calculations are in general very expensive.
>>>> I would suggest you run an example to see what to expect.
>>>> You might also try to perform a calculation on your system with minimal
>>>> computational parameters (very small cut-off, few/one k-points) just to see
>>>> that your run can indeed terminate smoothly. Then I would look for a set of
>>>> parameters which are a good compromise between computational time and the
>>>> accuracy you need.
>>>> You might also try to modify the parameter ecutfock to gain some speed.
>>>> For sure a hybrid functional calculation on a CNT+Fullerene system
>>>> might be rather challenging.
>>>> Best,
>>>> Dario
>>>>
>>>> On Wed, Aug 3, 2016 at 11:16 AM, Narendranath Ghosh <
>>>> ghosh.naren13 at gmail.com> wrote:
>>>>
>>>>> Dear all
>>>>>
>>>>>                    After optimizing a system "CNT+Fullerene" with
>>>>> "PBE" I am trying to calculate "scf" calculation with "PBE0" hybrid
>>>>> functional using  NC Pseudopotential.
>>>>>
>>>>> In output file I found "*convergence has been achieved in  15
>>>>> iterations" *But the job was not finished even after more than one
>>>>> week. I could not find any mistake in my input.
>>>>>
>>>>>
>>>>> Please suggest any idea.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
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