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[Anurag Chaudhry <anuragchaudhry@yahoo.co.uk>]

Hello Dr. Verstraete,

Thank you for your reply.

I am treating the system as metal as you mentioned (occopt 3).  The f-band splitting for the spin up channel (between the occupied and unoccupied f states) is ~2.1eV whereas the spin up/down f states are separated by ~ 4.0 eV (difference between the occupied spin up 4f and the spin down unoccupied 4f ).

will the results be any different if I specify occupation numbers using occopt 2 ?

I have read the paper you mentioned but I do not know how to go about LDA+U calculations with ABINIT without the PAW pseudopotentials.  I tried generating them myself (using atompaw) but without much success in the past.  If anyone can generously share the PAW psuedopotentials for few elements like Ce, La, Lu it would be a great help in my research.

best regards,
Anurag

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From: matthieu verstraete <matthieu.jean.verstraete@gmail.com>
To: forum@abinit.org
Sent: Monday, 19 January, 2009 2:08:00
Subject: Re: [abinit-forum] spin polarized vs. no spin

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