[QE-users] value of S^2 in LSDA

[Paolo Giannozzi]

There is a simple routine in CP that estimates the amount of "spin
contamination": CPV/src/spinsq.f90. Hope this helps (but I am not sure it
will!)

Paolo

On Sun, Jul 26, 2020 at 8:36 AM Christoph Wolf <wolf.christoph at qns.science>
wrote:

> Dear all,
>
> I am navigating in circles here, I hope someone can "kick" me in the right
> direction ;)
>
> When estimating the "spin-contamination" literature (e.g. JP Malrieu, Chem
> Rev 2014, 114, 429 ff) mentions that the degree of contamination is
> estimated by the deviation of <BS|S^2|BS> and <HS|S^2|HS> from their ideal
> (Ising wave-function type) values. I have a system in which the two
> spin-centers seem spatially well-separated and indeed I find that the LDOS
> indicates negligible overlap of the magnetic orbitals on the two centers.
> However I also wanted to check if the Noodleman condition is satisfied,
> e.g. if <S^2>_{HS}-<S^2>_{BS}~(S_max)^2.
>
> However, I can't figure out if this is calculated in PWSCF at some point?
> Or does literature suggest to calculate this "by hand" possibly from the
> output of the Hubbard U routine where I have account of the individual
> electrons?
>
> Any help is appreciated, have a great weekend!
>
> Best,
> Chris
>
> --
> Postdoctoral Researcher
> Center for Quantum Nanoscience, Institute for Basic Science
> Ewha Womans University, Seoul, South Korea
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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