[QE-users] Re DFPT of thin metal layer: convergence has not been achieved
nicola.marzari at epfl.ch
Tue Nov 13 01:51:11 CET 2018
On 13/11/2018 01:42, Christoph Wolf wrote:
> Dear all,
Last options would be alpha_mix and nmix_ph, while using a decent
smearing (.02 Ry, when in doubt)?
Here it is: https://www.quantum-espresso.org/Doc/INPUT_PH.html#idm36
Your alpha_mix is small, so maybe you tried. What about smaller? More
iterations in nmix?
The only method bound to converge would be a direct minimization of the
variational functional for linear-response theory, but that would be
major work to implement.
> thank you for your help so far. Unfortunately I am still not able to
> reach self consistency during the ph.x calculation. I have tested all
> smearing methods (and tetrahedra_opt), several smearing widths between
> 0.001 and 0.02, in-plane k-point grids up to 21x21x1 (121 k points) and
> relaxed the structure down to forces of 1e-6 a.u..
> whilst I can reach arbitrary scf accuracy
> ! total energy = -3634.01568752 Ry
> Harris-Foulkes estimate = -3634.01568752 Ry
> estimated scf accuracy < 5.9E-17 Ry
> there seems to be no way to avoid the "oscillating" behavior in ph.x
> Pert. # 1: Fermi energy shift (Ry) = -9.6471E-02 0.0000E+00
> iter # 100 total cpu time : 23216.2 secs av.it <http://av.it>.: 7.2
> thresh= 1.733E-04 alpha_mix = 0.100 |ddv_scf|^2 = 1.665E-09
> End of self-consistent calculation
> No convergence has been achieved
> This is very odd and very frustrating - I am curious if anyone else has
> encountered this for thin (7-11 ML) metal layers and has found a
> strategy to overcome this?
> Thanks in advance for your help, it is very much appreciated!
> Postdoctoral Researcher
> Center for Quantum Nanoscience, Institute for Basic Science
> Ewha Womans University, Seoul, South Korea
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> users at lists.quantum-espresso.org
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
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