[QE-users] Fermi-Surface Nesting

[Ramesh Kumar Kamadurai]

Dear Chiara
Thanks for your reply. Yes I was planning to compute dynamical
susceptibility and Nesting functions to sort out the issue. Professor
Kawamura suggested me that I can compute nesting functions within Fermi
surfer package itself. I will be exploring the new features. Thanks for
your suggestions and useful references.
Regards
Ramesh
Asst Professor
GITAM Vizag
India

On Mon, Aug 21, 2023, 4:19 AM Chiara Cignarella via users <
users at lists.quantum-espresso.org> wrote:

> Dear Kumar,
>
> In order to make sure you have a nesting of the Fermi surface you should
> plot the nesting function (the double deltas function); the points where
> you see the peaks are the nesting points of the Fermi surface.
>
> The  phonon softening in the phonon dispersion that you observe should be
> a Kohn anomaly. It is likely to be related to the Fermi nesting, but not
> straightforward.
>
> You can have a look at some of the literature about, like for example
> ”Johannes and Main PRB 77, 2008”, "Zhu X. Et al PNAS 2015", or more
> standard books like Khomskii “Basic aspects of quantum theory of solids”,
> Chapter 9 and 11.
>
> Best
> Chiara Cignarella
>
> PhD student
> EPFL
>
>
> > On 19 Aug 2023, at 18:13, ukawamura u <mkawamura at ds.itc.u-tokyo.ac.jp>
> wrote:
> >
> > Dear Dr.Kamadurai
> >
> > Maybe you are using FermiSurfer.
> > I added function to compute two kinds of nesting function namely
> > double-delta and Lindhard-type:
> >
> https://mitsuaki1987.github.io/fermisurfer/en/_build/html/ops.html#nesting-function
> > This version was released today.
> > https://github.com/mitsuaki1987/fermisurfer/releases/tag/2.4.0
> >
> > Best regards,
> > Mitsuaki Kawamura
> >
> > Mitsuaki Kawamura
> > Data Science Research Division, Information Technology Center, The
> > University of Tokyo
> > e-mail: mkawamura at ds.itc.u-tokyo.ac.jp
> >
> > 2023年8月16日(水) 15:06 Ramesh Kumar Kamadurai via users
> > <users at lists.quantum-espresso.org>:
> >>
> >> Dear All
> >> I am writing to get some clarification about the nesting of the Fermi
> surface. Since the FS geometry looks complex, I need help understanding it
> correctly. Sorry for asking non-QE-related question. I have calculated the
> Fermi surface for a conventional cell and projected it onto the primitive
> cell. When examining a slice along the 110 direction, I noticed two
> parallel lines at the boundary's edge. Further in the phonon calculation, I
> observed phonon softening (imaginary frequency) at the same M point. Is
> there a connection between this stitching of surfaces on the Fermi surface
> and the observed phonon softening, and finally, is there a nesting? I am
> attaching the relevant pictures. Thanks in advance for your suggestion.
> >>
> >> Best regards,
> >>
> >> K. Ramesh Kumar
> >>
> >> Assistant Professor
> >>
> >> Gandhi Institute of Technology and Management,
> >>
> >> Phone: +91 9895637981, +1 6782419790
> >>
> >> Email: kraamesh57 at gmail.com rkamadur at gitam.edu
> >>
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> > effects that the Russian military offensive has on their
> > country and on the free and peaceful scientific, cultural,
> > and economic cooperation amongst peoples
> > _______________________________________________
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> _______________________________________________
> The Quantum ESPRESSO community stands by the Ukrainian
> people and expresses its concerns about the devastating
> effects that the Russian military offensive has on their
> country and on the free and peaceful scientific, cultural,
> and economic cooperation amongst peoples
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
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