[QE-users] scf of organic molecule does not converge

[Bidault, Xavier]

I would say that an energy cutoff of 25 Ry is way too small. I also work on organic molecules, and I use 90 Ry (and 900 Ry for ecutrho) with PSlib 1.0.0 US to get errors lower than 1 meV/atom.

@Paolo: I wonder how relevant it is to use smearing in an organic compound (unless it has conducting or semi-conducting capabilities). Could you tell why it would be something to do?

Xavier B.
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Paolo Giannozzi <p.giannozzi at gmail.com>
Sent: Wednesday, June 23, 2021 2:04 AM
To: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] scf of organic molecule does not converge

It works decently well if you add a smearing (and a few more bands, but this is done automatically):
   occupations      = 'smearing'
   smearing         = 'gaussian'
   degauss          = 0.01

Paolo

On Wed, Jun 23, 2021 at 8:12 AM Haoran Wang <whr1130 at gmail.com<mailto:whr1130 at gmail.com>> wrote:
Hi QE users,

I have been trying to run the scf of a molecule below for many days. It never converged. The configuration is from Gaussian optimization, so it should be sensible. I did try other configurations obtained from MD simulations and still no convergence. I tried different pseudo-potentials (PBE-PAW, PBE-US, LDA-US) and also tried tuning the parameters (mixing_beta, mixing_mode, ecutrho...), still no convergence. Could somebody help me and see why this happens?

Thanks,
Haoran Wang
Utah State University

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--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222

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