In general I am as afraid as Gerhard Fecher that this question is at
least very difficult to answer. By definition one needs to calculate the
low field response of the electrons, and there is a whole bunch of
contributions, from the single electron orbital and spin-Pauli
contributions Peter mentions to quasiparticle contributions that are in
my understanding simply not present in the ground state calculated by
DFT. And there are questions of ground states with spin corelations,
temperature and field dependencies leading to changes from overall
paramagnetic to diamagnetic response ...
Reading Peters response I wonder about even a single electron
contribution and the NMR package in the case of metals: Does this
package calculate only the (paramagnetic) Pauli spin susceptibility? Or
is their Landau diamagnetism also included? For free electrons it
amounts to 1/3 of the Pauli spin susceptibility (see your favorite
textbook on the theory magnetism), so it is by no means safe to simply
assume its small.
Greetings,
Martin Pieper
Am 08.05.2017 20:19, schrieb Peter Blaha:
In an insulator/semiconductor you have only the orbital part of the
susceptibility. This can be calculated using our NMR package and such
a material will be diamagnetic.
In metals you have in addition a spin suszeptibility, which you can
trivially calculate using spin-polarized calc. and an external field.
Usually this part is paramagnetic. And then you have to see, which
part dominates ....
See also our NMR package.
Am 08.05.2017 um 16:28 schrieb Fecher, Gerhard:
I am afraid that this question can not be answered
and I doubt if any answer on this can be generalised to all kinds of
materials.
As an experimentalist my answer will be: measure the susceptibility
and it will tell you what your material is.
As you do not apply any magnetic field in your (non-spinpolarized)
calculation, the induced magnetic moment will be zero
and a) tells you that this is true for both, diamagnetic or
paramagnetic
What about b) ?
I tried it for Pt and indeed I find that the application of a magnetic
field induces a magnetic moment (spin polarized calculation !)
that is parallel to the applied field, and linearly dependent on its
size, as expected for a paramagnet.
However, I did not check whether the electrons in the closed shells
behave diamagnetic as they should.
I doubt that this will work for all materials as in most cases the
induced moment will be just to low to decide even if you use brute
force (very high field, very much k-points etc.)
If a ferro- or other "magnetic" solution is close, then the
application of the field may break the symmetry in such a way that you
run into this state instead of staying in the paramagnetic state.
Diamagnetism will probably not bee seen in Semiconductors.
You may try semimetallic graphite which is a "strong" diamagnet to see
whether it is possible to see any antiparallel allignment of induced
magnetic moments.
I did not further check, maybe there are some codes available to
calculate the suscebtibility of para- or diamagnetic materials.
Ciao
Gerhard
DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."
====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von
karima Physique [physique.kar...@gmail.com]
Gesendet: Montag, 8. Mai 2017 14:48
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] paramagnetic or diamagnetic
Thank you very much for your answer
I started a calculation in several magnetic phases (non-magnetic,
ferromagnetic and antiferromagnetic) and I found that the non-magnetic
phase is the most stable. so how can I know if the studied material
is a paramagnetic or diamagnetic material?
Thank you in advance
2017-05-08 8:06 GMT+02:00 Fecher, Gerhard
<fec...@uni-mainz.de<mailto:fec...@uni-mainz.de>>:
What distinguishes a paramagnetic from a diamagnetic material ?
a) at zero magnetic field the induced magnetic moment is zero for both
b) at external magnetic field the induced magnetiuc moment is parallel
/ antiparallel to the applied field.
c) both is true
d) none is true
There was already a discussion about paramagnetism, see
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg15029.html
Ciao
Gerhard
DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."
====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien
[wien-boun...@zeus.theochem.tuwien.ac.at<mailto:wien-boun...@zeus.theochem.tuwien.ac.at>]
im Auftrag von karima Physique
[physique.kar...@gmail.com<mailto:physique.kar...@gmail.com>]
Gesendet: Samstag, 6. Mai 2017 01:50
An: A Mailing list for WIEN2k users
Betreff: [Wien] paramagnetic or diamagnetic
Dear Wien2k users:
How I can know if the material is paramagnetic or diamagnetic with a
calculation.?
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---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564
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