Dear Dr. Giovanni Cantele Thank you very much for this helpful information.
After modifying the input, I found that the choice of *eopreg *also affects the result. I found the dipole value close to zero using the attached input, but I still don't know how to chose the value of the *eopreg. Would you mind to give me some more explanation on the eopreg?* With Regards On Tue, May 26, 2020 at 6:15 AM Giovanni Cantele < [email protected]> wrote: > An issue with your input is that you place the point where the external > saw-tooth potential > has a discontinuity in its derivative at emaxpos = 0.5 (it is in crystal > units, so because edir = 3, > it means that the potential depends on z and the discontinuity is at > (0,0,a/2)). > However, the CO2 molecule is placed along the x axis at fixed y = a/2 and > z = a/2. As such, > the discontinuity, which is unphysical since in serves to compensate the > spurious dipole field that > would arise as a consequence of the periodic boundary conditions, is > located in a region where the > charge density is not zero. emaxpos should be set in such a way that the > discontinuity il located > in the vacuum, in the region where the charge density is zero or in any > case very small. In your setup > it seems that a good choice would be emaxpos=0. > > Giovanni > > PS since you’re studying an isolated molecule, provided the size of your > supercell is sufficiently large, > the eigenvalues should exhibit no dependence on k. As a consequence, in > this case, a 4x4x4 sampling > of the Brillouin zone, should provide results equivalent to a gamma only > sampling. So, you can switch to > KPOINTS automatic > 1 1 1 0 0 0 > or, even better, > KPOINTS gamma > to make your calculation faster while keeping the same accuracy. > > On 27 May 2020, at 03:42, ENDALE ABEBE <[email protected]> wrote: > > Dear Experts, users and all > > I found the dipoles of CO2 calculated by Quantum ESPRESSO as : > > Computed dipole along edir(3) : > Elec. dipole 0.3112 Ry au, 0.7909 Debye > Ion. dipole 0.8137 Ry au, 2.0683 Debye > Dipole 41.9812 Ry au, 106.7055 Debye > Dipole field 0.5025 Ry au, > > I assumed the third value is the sum of the electronic and ionic > contributions. > The input and output files are attached herewith. > Since CO2 is non-polar molecule (with polar bonds), shouldn't the total > dipole moment be zero? > > -- > Endale Abebe > Program coordinator and Lecturer > Faculty of Materials Science and Engineering > Jimma Institute of Technology > Jimma University > P.O.Box 378, Jimma, Ethiopia > Mobile: +251921381598 > <CO2_nscf.out><CO2_nscf.in>_______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > > > -- > > Giovanni Cantele, PhD > > CNR-SPIN > c/o Dipartimento di Fisica > Universita' di Napoli "Federico II" > Complesso Universitario M. S. Angelo - Ed. 6 > Via Cintia, I-80126, Napoli, Italy > > e-mail: [email protected] <[email protected]> > [email protected] > Phone: +39 081 676910 > Skype contact: giocan74 > Web page: https://sites.google.com/view/giovanni-cantele > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users -- Endale Abebe Program coordinator and Lecturer Faculty of Materials Science and Engineering Jimma Institute of Technology Jimma University P.O.Box 378, Jimma, Ethiopia Mobile: +251921381598
CO2_scf.in
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