Dear Vipul, There could be two main explanations for your results: -A problem with the k-points you use to compute the bandstrucure: the grid for the cell and supercell must be consistent -An error in the supercell. Try comparing total energies: does the supercell have 8 times the total energy of the cell? Best, Dario Rocca
On Fri, Nov 25, 2016 at 7:47 AM, Vipul Shivaji Ghemud < [email protected]> wrote: > I have been using 8*8*8 for unit cell and 4*4*4 for supercell as my > supercell is 2*2*2 unit cell. > > > Dear Vipul, > > how many k-points did you use for the cell and for the supercell > > Best > > Dario > > > On Thu, Nov 24, 2016 at 6:23 AM, Vipul Shivaji Ghemud < > > [email protected]> wrote: > > > Hi all, > > I am working on a system of 9atoms in a unit-cell having bandgap of > 3.5eV; > > but I am considering the super-cell(4 unit-cells) then the bandgap is > > reduced by ~0.45eV for HSE06. The bandgaps are similar with GGA. Is it > due > > to the exchnage-correlation contribution of the increased number of > > electrons in the system, as the code QE considers unit-cell and > super-cell > > both a a single system? It's a bulk cubic system. I am facing similar > > problem with other systems also. > > > > > > > > -- > > Vipul S. Ghemud > > Ph.D. student. > > Dept of Physics, > > SPPU, Ganeshkhind, > > Pune- 411007. > > > > > > > -- > Vipul S. Ghemud > Ph.D. student. > Dept of Physics, > SPPU, Ganeshkhind, > Pune- 411007. > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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