Dear Bhamu, thank you for your email. My system is bulk CsPbBr3 and I do not have any problem with SCF self-convergence. Just the phonon calculation. Changing mixing_alpha did not lead to any significant improvement in my case....
Best, Chris On Wed, Jun 27, 2018 at 9:23 PM, Dr. K. C. Bhamu <kcbham...@gmail.com> wrote: > > > Hii Christoph, > > Could you please confirm whether your system is homogeneous or not? > > > If it is not a homogeneous then 'local T-F' scheme will be the best one. > > I recently solved my problem by using local TF. > > Also, you can reduce mixing parameter to 0.3 from 0.7 > > > > Kind regards > Bhamu > > Dr. K. C. Bhamu > National Postdoctoral Fellow, > Physical and Materials Chemistry Division > CSIR-NCl, Pune > India > Mob. No. +91-7888227869 > > On Wed, Jun 27, 2018 at 5:46 PM, Christoph Wolf < > wolf.christoph@qns.science> wrote: > >> Dear all, >> >> I have recently encountered an "interesting phenomenon". >> >> Let's say I have determined the (zone boundary phonon frequency) >> convergence parameter for a unit cell to be a k-grid of 6x6x6 and a >> ecutwfc=120 Ry. If I now take a 2x2x2 supercell of the material (using the >> relaxed cell as reference) I (naively) assumed that that would translate to >> a 3x3x3 k-grid, however I can never manage to converge phonons with that >> kind of setting as during the initial electric fields calculation the >> minimization will start to oscillate like this: >> >> >> iter # 17 total cpu time : 8249.5 secs av.it.: 1.8 >> thresh= 2.804E-05 alpha_mix = 0.700 |ddv_scf|^2 = 1.396E-07 >> >> iter # 18 total cpu time : 8353.6 secs av.it.: 1.0 >> thresh= 3.737E-05 alpha_mix = 0.700 |ddv_scf|^2 = 1.506E-08 >> >> iter # 19 total cpu time : 8876.9 secs av.it.: 15.4 >> thresh= 1.227E-05 alpha_mix = 0.700 |ddv_scf|^2 = 6.969E-08 >> >> iter # 20 total cpu time : 9303.8 secs av.it.: 12.1 >> thresh= 2.640E-05 alpha_mix = 0.700 |ddv_scf|^2 = 6.076E-08 >> >> iter # 21 total cpu time : 9751.4 secs av.it.: 12.9 >> thresh= 2.465E-05 alpha_mix = 0.700 |ddv_scf|^2 = 3.246E-08 >> >> iter # 22 total cpu time : 10145.8 secs av.it.: 11.1 >> thresh= 1.802E-05 alpha_mix = 0.700 |ddv_scf|^2 = 3.519E-08 >> >> iter # 23 total cpu time : 10542.9 secs av.it.: 11.2 >> thresh= 1.876E-05 alpha_mix = 0.700 |ddv_scf|^2 = 3.168E-09 >> >> >> Is this a common problem or am I doing something completely wrong...? >> >> Your help is very much appreciated! >> >> Best, >> Chris >> >> -- >> Postdoctoral Researcher >> Center for Quantum Nanoscience, Institute for Basic Science >> Ewha Womans University, Seoul, South Korea >> >> >> _______________________________________________ >> users mailing list >> users@lists.quantum-espresso.org >> https://lists.quantum-espresso.org/mailman/listinfo/users >> > > -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea
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