[QE-users] Born Huang and Huang invariance conditions

[Elio Physics]

Dear professor Marzari and Changpeng,

Thanks for the valuable information.

I will have a look at these options.

Regards

________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Changpeng Lin via users <users at lists.quantum-espresso.org>
Sent: Wednesday, October 25, 2023 1:25 PM
To: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Subject: Re: [QE-users] Born Huang and Huang invariance conditions


Yes, it’s implemented in matdyn, as the Invariance conditions are made on real-space force constants. For q2r, there is a related tag “write_lr” due to this implementation, to deal with the subtlety of long-range interactions in polar solids.

One can find an example input in QE test suite for 2D phonon calculations with those corrections:
https://gitlab.com/QEF/q-e/-/tree/develop/test-suite/ph_2d

Best,
Changpeng
---- Replied Message ----
>From    Nicola Marzari<nicola.marzari at epfl.ch> <mailto:nicola.marzari at epfl.ch>
Date    10/25/2023 17:02
To      <users at lists.quantum-espresso.org> ,
<mailto:users at lists.quantum-espresso.org>Changpeng Lin<changpeng.lin at epfl.ch> <mailto:changpeng.lin at epfl.ch>
Subject         Re: [QE-users] Born Huang and Huang invariance conditions


Thanks - thhis is the paper:

https://www.nature.com/articles/s41524-022-00920-6

and in the matdyn
(https://www.quantum-espresso.org/Doc/INPUT_MATDYN.html) this is the
option 'all'.

Not sure about q2r - should be there as well, but I do not see it - but
maybe I'm missing something?

nicola



On 25/10/2023 16:44, Elio Physics wrote:
Dear all,

There have been several papers discussing the use of the so-called
Born-Huang and Huang invariance conditions to soothe the possible
negative frequencies that may arise in the long wavelength limit (q->0,
near the G point) in the phonon dispersion of 2D and 1D material.

Is there a specific flag in the ph.x input file that needs to be turned
on to incorporate such corrections?

Regards

Elie Moujaes
Adjunct professor level 4
Federal University of Rondonia
Brazil

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----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, SNSF
Head, Laboratory for Materials Simulations, Paul Scherrer Institut
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