[QE-users] Quantum about inconsistent K 111 and gamma sampling

[Shimin ZHANG]

Hi ,
Thank you for the prompt response.
I think I figured out the problem. The inconsistency appears when computing nscf with gamma based on density from scf with k point sampling. I think this caused by some extrapolation problem?

Best,
Shimin

On Jul 18, 2025, at 5:04 AM, Pietro Davide Delugas <pdelugas at sissa.it> wrote:


Hello
In general, well-converged results in the Gamma-only mode and results with the k-point modality using Gamma as the single k-point should be consistent. About specific cases, it would be beneficial to have a particular example to talk about.
Pietro
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Shimin ZHANG via users <users at lists.quantum-espresso.org>
Sent: Thursday, July 17, 2025 21:17
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: [QE-users] Quantum about inconsistent K 111 and gamma sampling

Dear QE community,

I have a general question about getting consistent result between K 111 and K gamma sampling.
I have observed this inconsistency in multiple systems, especially the 2D material.

I wonder if this problem is numerical, or caused by the gamma trick assumption which state that the wave function at gamma point has to be real? If this problem is not numerical, does that mean the atomic structure constructed somehow break the boundary condition?

I am looking forward to hear more insight about it.

Best,
Shimin
______________
PhD candidate,
Department of Materials science and Engineering,
University of Wisconsin, Madison
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