Dear Asad,
please also answer to the list ;) ("reply all")No! It's either dipfield = .true. or assume_isolated ='2d'. If you want to simulate "a real" 2D system using the Coulomb cutoff you don't need to correct due to the systems dipole. And if you correct with the artificial dipole, cutting of the Coulomb will result in something bad/weird... Actually, I don't know if this will work at all.
So, either dipfield = .true. or assume_isolated ='2d' Thomas On 11/13/18 11:45, Asad Mahmood wrote:
Thanks Thomas for reply. So I need to include both flags(i.e dipfielf = .true and assume_isolated ='2d' ) in relax or structure optimization calcations ?On Tue, Nov 13, 2018, 3:11 PM Thomas Brumme <[email protected] <mailto:[email protected]> wrote:Dear Asad, What is the benefit of using dipfield=.true.? Well, the benefit is that you get the correct electronic structure, energetics, and so on. As you want to simulate a 2D system with 3D boundary conditions this is the only correct way if you have an asymmetric system (in the z-direction, assuming the 2D system is in xy). Well, not the only correct way. Recently a Coulomb cutoff technique was implemented in QE, check input flag assume_isolated='2D' Regards Thomas P.S.: If you have a dipole in your system you'll see that properties (especially the total energy) will change with increasing vacuum region. If you increase it, you'll minimize the eigenfunction overlap between the repeated layers but the Coulomb interaction will never be zero and thus you can get wrong results - and this will be worse for larger dipole, e.g., the flourinated graphene. On 11/13/18 08:38, Asad Mahmood wrote:Hi, I have a hexagonal graphene(or any other) monolayer and I hydrogenate(or flourinate, etc.) on the top surface only (single sided). Is there need to use flag dipfield = .true ? What is benefit or disadvantage of using this flag for optimization of L.C or bond length? I am using 20 angstrom vacuum between two layers to avoid mutual influence. _______________________________________________ users mailing list [email protected] <mailto:[email protected]> https://lists.quantum-espresso.org/mailman/listinfo/users-- Dr. rer. nat. Thomas BrummeWilhelm-Ostwald-Institute for Physical and Theoretical Chemistry Leipzig University Phillipp-Rosenthal-Strasse 31 04103 Leipzig Tel: +49 (0)341 97 36456 email:[email protected] <mailto:[email protected]>
-- Dr. rer. nat. Thomas Brumme Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry Leipzig University Phillipp-Rosenthal-Strasse 31 04103 Leipzig Tel: +49 (0)341 97 36456 email: [email protected]
_______________________________________________ users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
