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

[Narendranath Ghosh]

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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>>
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