Dear Dr. Fthenakis Thank you very much for your helpful guidance, Best wishes, Nadia
On Sun, Jul 26, 2015 at 12:25 PM, <fthe...@iesl.forth.gr> wrote: > Nadia > you are not right. A denser k-point sampling COULD be used, but it is not > necessary. In the 2-dimensional case you have the E(k_x,k_y,k_z=0) > function for the energy, instead of the more general 3-dimansional > E(k_x,k_y,k_z). Therefore, the accuracy of the E(k) expression would be > the same. Just ensure that if you have a denser k-points sampling, DOS > converges. > > Best > Zacharias Fthenakis > > > Dear Dr. Papior, > > > > Since my system is a slab, so the scattering occurs in two dimensions > (the > > transport direction and also the transverse direction), According to two > > directions, I think that denser k point sampling along two directions > must > > be used to calculate the transmission. Am I right? > > > > Thanks in advance, > > > > Best regards, > > Nadia Salami > > > > On Sun, Jul 26, 2015 at 11:53 AM, Nadia Salami <nadiasala...@gmail.com> > > wrote: > > > >> Dear Dr. Papior, > >> > >> Since my system is a slab, so the scattering occurs in two dimensions > >> (the > >> transport direction and also the transverse direction), According to two > >> directions, I think that denser k point sampling along two directions > >> must > >> be used. Am I right? > >> > >> Thanks in advance, > >> > >> Best regards, > >> > >> Nadia Salami > >> > >> On Sat, Jul 25, 2015 at 11:46 AM, Nick Papior <nickpap...@gmail.com> > >> wrote: > >> > >>> > >>> > >>> 2015-07-25 6:55 GMT+00:00 Nadia Salami <nadiasala...@gmail.com>: > >>> > >>>> Dear Transiesta users, > >>>> > >>>> I don’t know how to determine correct k point sampling for the > >>>> Transiesta as well as Tbtrans calculations. > >>>> > >>> You converge using the same principles as standard DFT, for transport > >>> calculations however, you converge the averaged transmission. > >>> > >>>> In details, I have determined k-point sampling for the electrode of my > >>>> system from the energy convergence test, that leads to the following > >>>> sampling > >>>> > >>>> %block kgrid_Monkhorst_Pack > >>>> > >>>> 1 0 0 0.0 > >>>> > >>>> 0 2 0 0.0 > >>>> > >>>> 0 0 4 0.0 > >>>> > >>>> %endblock kgrid_Monkhorst_Pack > >>>> > >>>> > >>>> > >>>> Must the k grid along the transport direction (i.e. kz) be increased > >>>> to > >>>> simulate the semi-infinite lead (electrode)? > >>>> > >>> I would always use as many k-points in the z-direction as you can (the > >>> more k-points, the better description of the self-energy you get). > >>> I typically use 100, if that proves too much, I try with 50. > >>> > >>>> Moreover I know that, the denser k-point sampling must be used to > >>>> calculate the transmission using Tbtrans utility. Must kx and ky be > >>>> increased? For Tbtrans calculation or both of Transiesta and Tbtrans > >>>> calculations? (Also I know that kz only is utilized to calculate > >>>> siesta > >>>> calculation in the scattering region.) > >>>> > >>> Transiesta calculates the density, tbtrans calculates the transport. > >>> > >>>> Finally, how to converge the k-point sampling for the transmission > >>>> calculation? > >>>> > >>>> It will be highly appreciated your comments and guidances. > >>>> > >>>> Thanks in advance, > >>>> > >>>> Best regards, > >>>> > >>>> Nadia Salami > >>>> > >>>> > >>>> > >>> > >>> > >>> > >>> -- > >>> Kind regards Nick > >>> > >> > >> > > > > > ********************************************************* > Dr Zacharias G. Fthenakis > Research Associate > Institute of Electronic Structure and Laser (I.E.S.L.) > Foundation for Research and Technology Hellas (FO.R.T.H.) > Vassilika Vouton P.O. Box 1527 71003 Heraklion Crete Greece > Phone +30 2810 391824 > FAX +30 2810 391305 > webpage: http://esperia.iesl.forth.gr/~fthenak > ********************************************************** > >
