Thank you a lot , David Foster, Giovanni Cantele. Appreciate your response Anik Kumar Mondol Bangladesh University of Engineering and Technology
On Wed, Nov 29, 2017 at 3:30 PM, Giovanni Cantele < [email protected]> wrote: > Hi, if you want to study a nanowire, I do not see the reason why to > optimise the unit cell along x and y directions. > Either freeze these two degrees of freedom in vc-relax or, much simpler, > change c parameter (lattice parameter along the z direction) > and evaluate E(c) (total energy as a function of c). A parabolic fit will > help you in finding the lowest energy configuration. > > Generally speaking, to establish whether the vacuum is enough, calculate > in at least one case the property you are interested in for two different > values of the vacuum and see if any appreciable change is observed. > Another check is that the band structure should be flat (no dispersion) > along x and y > > Giovanni > > > > On 29 Nov 2017, at 06:28, Anik Mondol <[email protected]> wrote: > > Dear Users, > I am doing a DFT calculation of GaN nanowires, While designing the > nanowire (approximately 10 A diameter) , I had added around 10 A of vacuum > on x and y direction. Now I have performed a vc-relax calculation before > band calculation, the cell volume has shrunk . The vacuum has decreased . > Now to make sure the results don't be affected by the identical replicas , > at least how much vacuum is needed ? Now, that the vacuum has shrunk, will > that impose any effect on results in this respects. I mean, How can I be > sure this vacuum is enough? > > Mondol Anik Kumar > Bangladesh University of Engineering and Technology > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > > > -- > > Giovanni Cantele, PhD > CNR-SPIN > c/o Dipartimento di Fisica > Universita' di Napoli "Federico II" > Complesso Universitario M. S. Angelo - Ed. 6 > Via Cintia, I-80126, Napoli, Italy > e-mail: [email protected] <[email protected]> > Phone: +39 081 676910 <+39%20081%20676910> > Skype contact: giocan74 > > ResearcherID: http://www.researcherid.com/rid/A-1951-2009 > Web page: http://people.fisica.unina.it/~cantele > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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