Hi, Thank you for the response. I have some confusion. If I define atoms in a unit cell and then define k1 k2 k3 (k points) it will indicate a 3D system right? If I define k1 k2 1, it will indicate a 2D system in the xy plane, 1 1 k3 (1D system) and 1 1 1(0D system). Then why would the calculation be considered computationally large if I define 10 nm width ( rather I reduce my system size from infinite to 10 nm)? Can you explain it to me?
FOr example, graphene Atomic Positions C 0.3333333 0.666666 0.5 C 0.6666666 0.333333 0.5 K_Points 12 12 1 0 0 0 pw.x < scf.in > scf.out ph.x <ph.in>ph.out q2r.x < q2r.in >q2r.out matdyn.x<matdyn.in>matdyn.out This provides phonon dispersion for graphene which is infinitely long in the x and y plane. If it works out for some reasonable time. Why does it take time for the system which is infinitely long in x direction and y direction to have a finite width of 10 nm (24 unit cells)? Thank you Best Jahid On Sat, Dec 24, 2022 at 5:31 AM PAULATTO Lorenzo <[email protected]> wrote: > Dear Jahid, you have to decide precisely what you want, than you may be > able to simulate it in different ways. A width of 10nm is probably too > large for a direct DFT calculation of phonons, in this case you can use the > phonons for the unit cell and add the finite size as a perturbation with > Green function methods. I know a paper where this is done, but there are > probably others, and other methods. > https://hal.archives-ouvertes.fr/hal-03011389 > > > Hth > > > LP > ------------------------------ > *From:* users <[email protected]> on behalf of Md. > Jahid Hasan Sagor <[email protected]> > *Sent:* Saturday, December 24, 2022 10:17:28 AM > *To:* Quantum ESPRESSO users Forum > *Subject:* [QE-users] Phonon Dispersion of graphene > > Hi, > > Please help if you can. I am trying to find out the dispersion relation of > graphene. I know that to find out the relation I have to use pw.x, ph.x, > q2r.x and matdyn.x. But the problem is, after applying all the packages, I > might get a phonon dispersion relation of graphene which is infinitely long > in x and y direction. However, in my model I am using a finite width of > graphene around 10nm (24 unit cell in the vertical direction). Which > command in QE can do this for me so that I can model a graphene which is > infinitely long in x direction and 10 nm in y direction? > > Best Regards > Md Jahid Hasan > _______________________________________________ > The Quantum ESPRESSO community stands by the Ukrainian > people and expresses its concerns about the devastating > effects that the Russian military offensive has on their > country and on the free and peaceful scientific, cultural, > and economic cooperation amongst peoples > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
