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Re: [abinit-forum] spin polarized vs. no spin

From: "matthieu verstraete" <matthieu.jean.verstraete@gmail.com>
To: forum@abinit.org
Subject: Re: [abinit-forum] spin polarized vs. no spin
Date: Mon, 19 Jan 2009 11:08:00 +0100
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Hello,

I have run calculations with no spin polarization for these systems. A typical total DOS has Ce 4f electron state inside the host bandgap, i.e., there is a gap between 4f and the valence band maximum (VBM). Recently I repeated a calculation (same goemetry and everything else same) except for spin polarization. Now the spin polarized DOS shows a different 4f - VBM gap.

The difference in energy may come from the intra-f state coulomb repulsion: in the spin polarized case you are sharing 1 electron among 7 states instead of 14 (provided you are treating the system as a metal?) What is the f-band splitting?

What you probably need to do is use LDA+U and PAW (probably nspinor 2, but at least nsppol 2) to get the splitting correct. This will also affect the offset wrt the VBM.

See Phys. Rev. B 77, 155104 (2008) [10 pages] " gamma

and

cerium: LDA+U calculations of ground-state parameters" by

Amadon, F. Jollet, and M. Torrent for some parameters and Ce in PAW/ABINIT

Matthieu

The 4f for Ce has only 1 electron in the system the spin up and spin down differ by only 1 electron. I do not understand how spin polarization vs. no spin calculations should give different results for the filled 4f - VBM gap ?

Any suggestions/comments are welcome.

All calculations are with TM pseudopotentials. LDA and LSDA were used for no spin and spin polarized calculations.

I did the calculations for the same compound with VASP (PAW, PBE) and found that it gives the same 4f-VB gap for spin polarized as well as no spin calculations.

best regards,
Anurag

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Matthieu Verstraete

European Theoretical Spectroscopy Facility (ETSF)
Dpto. Fisica de Materiales,
U. del Pais Vasco,
Centro Joxe Mari Korta, Av. de Tolosa, 72, Phone: +34-943018393
E-20018 Donostia-San Sebastian, Spain Fax : +34-943018390

Mail : matthieu.jean.verstraete@gmail.com
http://www-users.york.ac.uk/~mjv500

[abinit-forum] build netcdf library, kong, 01/16/2009
- Re: [abinit-forum] build netcdf library, Alain Jacques, 01/16/2009
  - Re: [abinit-forum] build netcdf library, Lingzhu Kong, 01/18/2009
    - [abinit-forum] spin polarized vs. no spin, Anurag Chaudhry, 01/19/2009
      - Re: [abinit-forum] spin polarized vs. no spin, matthieu verstraete, 01/19/2009
        
        Re: [abinit-forum] spin polarized vs. no spin, Anurag Chaudhry, 01/19/2009