Dear Lorenzo, I appreciate your help. I should study more and then continue.
Thanks, Vatankhah On Mon, Dec 3, 2012 at 8:32 PM, Lorenzo Paulatto < lorenzo.paulatto at impmc.upmc.fr> wrote: > On 3 December 2012 17:34, zahra vatankhah <vatankhah.z at gmail.com> wrote: > >> Dear Lorenzo, >> For more detail, I performed the scf run for graphene/h-BN bilayer with >> both 001 and 111. The Fermi energy was 1.4072 and 1.2002 eV for 111 and 001 >> respectively. Then I plot the DOS for both and I set the Fermi to zero, but >> they were different. For 111, the Fermi is in the middle of the small gap >> whereas the fermi crosses the states for 001.( The attached picture is the >> total DOS with 001 without setting fermi to zero, the red line is the fermi >> obtained from scf run with 001 and the green line is the fermi with >> 111.(the correct fermi should be in the middl of the gap)). >> > > Dear Zahra, > it looks like the difference is very small, especially sine you have a > gap. Keep in mind that, if you have a gap, in the limit of zero smearing > the Fermi energy can go anywhere in the gap. This is just a complicated > way to say that there is no Fermi energy in insulators. > > On the other hand, both your calculations are wrong; if you want to > simulate non-interacting planes - separated by some vacuum along Z - than > you cannot shift the kpoints along Z. Be sure to have well understood this > point before continuing, as it really is important. Check on some solid > state book how the periodicity of wavefunctions is related to their > k-point, and what kind of periodicity do you expect for your system > (included the artificial periodicity along Z). By setting the shift along Z > you force the wavefunctions from two artificial replicas of the graphene > bilayer to hybridize with each other, which is an unphysical effect. > > bests > > -- > Dr. Lorenzo Paulatto > IdR @ IMPMC -- CNRS & Universit? Paris 6 > phone: +33 (0)1 44275 084 / skype: paulatz > www: http://www-int.impmc.upmc.fr/~paulatto/ > mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05 > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20121203/ef73444f/attachment.html
