Thanks, Iurii. Yes, the spectrum with gamma point is quite reasonable but do not match with the experimental observation. It could be some other issue.
However, I am wondering how to do the TDDFT calculation for a doped/defected structure with extra electron or hole. I tried to use turbo_davidson starting from i) scf calculation with npsin= 2 and total magnetization and turbo_davidson does not work since I believe it does not for spin-polarized system, then, I tried ii) scf calculation without any spin-polarization and the scf calculation did not run since it cannot work with an extra charge and 'fixed' occupation, and, finally, iii) scf with smearing but turbo_davidson does not support scf calculation with smearing (ref: https://lists.quantum-espresso.org/pipermail/users/2017-January/037363.html) I believe in this case I cannot use TDDFT of QE to calculate absorption spectra of a defected or doped structure. Am I right here? Best, Abhirup ------------------------------------------------------------------------------------------------------------------------------------- Abhirup Patra Postdoctoral Research Fellow Department of Chemistry University of Pennsylvania On Wed, Dec 18, 2019 at 4:00 AM Timrov Iurii <[email protected]> wrote: > Dear Abhirup, > > > > However, I am not sure with the number of atoms (~120 or more) GW-BSE > calculations with supercell is actually feasible. > > > Yes, I understand the issue. I do not know if it is feasible. You may try > to use e.g. Yambo and see how it goes. Otherwise, since you have already > quite a big cell, maybe with k=0 you obtain quite a reasonably converged > spectrum (to be checked w.r.t. the cell size) at the TDDFT level in the > adiabatic approximation. > > > Regards, > > Iurii > > > -- > Dr. Iurii Timrov > Postdoctoral Researcher > STI - IMX - THEOS and NCCR - MARVEL > Swiss Federal Institute of Technology Lausanne (EPFL) > CH-1015 Lausanne, Switzerland > +41 21 69 34 881 > http://people.epfl.ch/265334 > ------------------------------ > *From:* users <[email protected]> on behalf of > Abhirup Patra <[email protected]> > *Sent:* Tuesday, December 17, 2019 4:47:01 PM > *To:* Quantum ESPRESSO users Forum > *Subject:* Re: [QE-users] k-point algorithm is not tested yet turbo > davidson > > Thanks very much, Iurii. I really appreciate your answer and it does make > sense to me. With gamma point only it works fine. And, you are right, my > system is a solid and I am > trying to simulate the optical spectrum. However, I am not sure with the > number of atoms (~120 or more) GW-BSE calculations with supercell is > actually feasible. > > Best, > Abhirup > > ------------------------------------------------------------------------------------------------------------------------------------- > Abhirup Patra > Postdoctoral Research Fellow > Department of Chemistry > University of Pennsylvania > > > On Tue, Dec 17, 2019 at 7:50 AM Timrov Iurii <[email protected]> wrote: > >> Dear Abhirup, >> >> >> As you can see from the error message of the turbo_davidson code, the >> k-points algorithm is not supported. Only Gamma point sampling can be used. >> >> >> If I understand correctly, your system is a solid, right? And you want to >> use a unit cell with a k-points mesh, right? The turbo_davidson cannot be >> used in this case. You may try to use a supercell with a Gamma point >> sampling. But be careful when using TDDFT in the adiabatic approximation >> for the absorption spectroscopy of solids. I recommend that you check >> literature on this topic. Maybe you will need to resort to the BSE approach. >> >> >> HTH >> >> >> Iurii Timrov >> >> >> -- >> Dr. Iurii Timrov >> Postdoctoral Researcher >> STI - IMX - THEOS and NCCR - MARVEL >> Swiss Federal Institute of Technology Lausanne (EPFL) >> CH-1015 Lausanne, Switzerland >> +41 21 69 34 881 >> http://people.epfl.ch/265334 >> ------------------------------ >> *From:* users <[email protected]> on behalf of >> Abhirup Patra <[email protected]> >> *Sent:* Monday, December 16, 2019 6:12:08 PM >> *To:* Quantum ESPRESSO users Forum >> *Subject:* [QE-users] k-point algorithm is not tested yet turbo davidson >> >> Hello, >> >> I am trying to use turbo_davidson starting from a SCF calculation using >> PBE without smearing and spin-polarization. This system is a non-metal with >> bandgap of 2.6 eV. I gave uniform k-mesh as follows for the bcc structure >> with lattice constant of 10.34 angstrom. >> >> K_POINTS {crystal_b} >> 9 >> 0.0 0.0 0.0 0 >> 0.0 -0.5 0.0 0 >> 0.0 -0.5 0.5 0 >> 0.5 -0.5 0.5 0 >> 0.5 -0.5 0.0 0 >> 0.5 0.0 0.0 0 >> 0.0 0.0 0.0 0 >> 0.0 0.0 0.5 0 >> 0.5 0.0 0.5 0 >> >> &lr_input >> prefix = 'pristine_pbe' >> outdir = './' >> ! wfcdir = './' >> / >> &lr_dav >> num_eign = 35, >> num_init = 70, >> num_basis_max = 200, >> start = 0.0d0 >> finish = 3.5d0 >> step = 0.001d0 >> broadening = 0.005d0 >> / >> >> However, I am getting the following error: >> >> Error in routine lr_readin (1): >> k-point algorithm is not tested yet >> >> I am wondering if there is a simple way out to this problem other than >> explicitly testing different k mesh combinations. >> >> Best, >> Abhirup >> >> ------------------------------------------------------------------------------------------------------------------------------------- >> Abhirup Patra >> Postdoctoral Research Fellow >> Department of Chemistry >> University of Pennsylvania >> _______________________________________________ >> 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 > > _______________________________________________ > 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
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