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 <roc...@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.nare...@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 <roc...@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.nare...@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. >>>> >>>> >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Pw_forum mailing list >>>> Pw_forum@pwscf.org >>>> http://pwscf.org/mailman/listinfo/pw_forum >>>> >>> >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum@pwscf.org >>> http://pwscf.org/mailman/listinfo/pw_forum >>> >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum@pwscf.org >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > _______________________________________________ > Pw_forum mailing list > Pw_forum@pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum >
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