[Wien] paramagnetic or diamagnetic

Tue May 9 13:28:22 CEST 2017

JPCC 119, 19390 (2015) for simple metals and
PRB 89, 014402 (2014) for insulators

On 05/09/2017 12:56 PM, pieper wrote:
>
> 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-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von
>>> karima Physique [physique.karima at 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
>>> <fecher at uni-mainz.de<mailto:fecher at 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-bounces at zeus.theochem.tuwien.ac.at<mailto:wien-bounces at zeus.theochem.tuwien.ac.at>]
>>> im Auftrag von karima Physique
>>> [physique.karima at gmail.com<mailto:physique.karima at 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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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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