[QE-users] dipole correction - "saggy" electrostatic potential?

2018-06-27 Thread Christoph Wolf
Dear all, I am still observing something strange in my slab + dipole correction calculation that I do not fully understand. When using dipfield+tefield (eopreg and emaxpos well within the vacuum region) I encounter a "saggy" electrostatic potential (plot_num=11) despite the sawtooth efield

Re: [QE-users] phonon convergence problem of supercells

2018-06-27 Thread Christoph Wolf
Dear Jay, thank you for your suggestion. I tried decreasing mixing_alpha and increasing nmix_ph to 5 (this seems to be the maximum) but it does not help. Convergence can be achieved by increasing the k-grid back to the original size but that would basically mean I over-sample the BZ now by a

Re: [QE-users] ?==?utf-8?q? phonon convergence problem of supercells

2018-06-27 Thread JAY Antoine
Dear Christoph, Try to decrease alph_mix to 0.1. Is it enough to converge? Best regards, Antoine Jay On Wednesday, June 27, 2018 14:16 CEST, Christoph Wolf wrote:  Dear all, I have recently encountered an "interesting phenomenon". Let's say I have determined the (zone boundary phonon

Re: [QE-users] phonon convergence problem of supercells

2018-06-27 Thread Christoph Wolf
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

[QE-users] phonon convergence problem of supercells

2018-06-27 Thread Christoph Wolf
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