I don't think you can draw a general conclusion - a 2D material (or a 3D
one) for a given geometry will have one or a few or many or infinite
energy minima/selfconsistent states, where the global minimum and the
local minima can be non-magnetic, ferromagnetic, or antiferro or
ferrimaginetic, in primitive cells or larger supecells, or display spin
spirals.
For a given geometry, each of this magnetic orders will lead to some
small relaxations that can break symmetry or not, can be commensurate or
incommensurate; ultimately, for every magnetic pattern there will be a
supercell (maybe large, if incommensurate) in which the phonons are
positive.
Of course, DFT or DFT+U+V or hybrids are approximate, so the
computational truth of an approximate theory is different from reality,
that in itself is not always truthful.
Hope this helps!
But to get a sense of the mess in which we are in, you could check this:
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=YjHKNAUAAAAJ&cstart=20&pagesize=80&sortby=pubdate&citation_for_view=YjHKNAUAAAAJ:v_xunPV0uK0C
(in press in npj computational materials).
nicola
On 09/04/2024 13:17, Zimmi Singh wrote:
Dear community and Developers,
I am reaching out to you to get some clarity regarding the dynamic
stability of a 2D ferromagnet, 2H-VSe2. For my research, I have to
calculate the thermal conductivity (using phono3py) of both its
ferromagnetic and non-magnetic structures. My calculations (using
PBE-PAW) suggest that the ferromagnetic phase (which is the favorable
ground state) is dynamically stable, whereas the non-magnetic phase is
unstable with negative frequencies in the phonon dispersions for one of
the acoustic modes.
On this topic, there are three published literature available, two
suggesting dynamic stability for both structures
(doi:10.1039/d2nh00429a, 10.1039/d3cp00008g), whereas the third
indicates that the non-magnetic state has one mode with negative
frequency (doi: 10.1007/s10853-021-06311-4, Figure S6).
Should the non-magnetic counterpart of a magnet be dynamically unstable
at zero kelvin? Can anyone shed some light on this?
--
*Best Regards*
Zimmi Singh
/Research_Scholar
/
/Department of Metallurgical and Materials Engineering
Indian Institute of Technology, Kharagpur
Kharagpur, India/
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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
Contact info and websites at http://theossrv1.epfl.ch/Main/Contact
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people and expresses its concerns about the devastating
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country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
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Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
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