[Wien] About the magnetic moment of vanadium in vanadium sulphide

[pieper]

High A. Reggad,

substitute V for Cr in Prof. Fecher's questions, otherwise I am with 
him.

In case you refer by 'almost zero' to the 0.05 mu_B I seem to recall 
from your original question, and now wonder about some fundamental 
discrepancy between the supposed experimental Pauli paramagnetism and 
your supposed antiferromagnetism: Take a VERY close look at both, 
experiment AND calculations.

It is not trivial to experimentally distinguish a PM from an AF with 
such a small moment, especially if you have no idea that there is a Tc, 
let alone where it is. The, say T-dependant SQUID, measurement could 
start already in the AF state if Tc is above RT and never realize the 
state is already AF. Or maybe Tc is below the lowest T the experimental 
set-up could reach?

It is equally not trivial to establish an AF ground state with that 
precision from DFT. Did you consider MMI of V as convergence criterium? 
Did you check convergence to that precision with respect to RKMAX, 
k-mesh, ... ? Did you keep the k-mesh (symmetries) between your 
calculations of the PM and the AF? Did you force the AF structure in 
your calculation? Did you try what happens if you don't impose it? Are 
you shure about your structural data? Did you do structural relaxation? 
Does structural relaxation influence your result of a magnetic ground 
state? What about the influence of the xc-potential? Did you do eece 
with LSDA or with PBE-GGA or with ...?

And what about other physical properties? Maybe most important, is the 
stuff metallic/insulating in experiment/calculations?

In case your question is about this horrible violation of Hund's rules, 
I repeat my former suggestion: Take a close look at the assumptions 
these rules rely on. And never forget that any law and rule of physics 
is valid only within some domain more or less clearly defined by such 
assumptions.



---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 05.09.2017 07:45, schrieb Fecher, Gerhard:
> About what moment are you talking,
> the total magnetic moment or the magnetic moment of the Cr atoms ?
> 
> Did you start your EECE calculation from a regular GGA calculation
> that had no magnetic moments at the Cr ?
> 
> 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
> Abderrahmane Reggad [jazairdz at gmail.com]
> Gesendet: Dienstag, 5. September 2017 00:29
> An: wien at zeus.theochem.tuwien.ac.at
> Betreff: Re: [Wien] About the magnetic moment of vanadium in vanadium 
> sulphide
> 
> Thanks martin
> 
> Experimentally they found that the vanadium sulphide is a pauli
> paramagnetic but I have found it to be antiferromagnetic like other
> transition metal sulphides but the magnetic moment value equals almost
> zero despite the fact that vanadium has 3 inpaired electrons.
> 
> Best regards
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html