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[matthieu verstraete <matthieu.jean.verstraete@gmail.com>]

Hello, my turn to ask a question:

I am using LDA+U with the latest (pre-release) abinit 5.7, on ifort 9.1/itanium/mpi (tests pass fine), trying to do calculations in LDA+U of alloys of d and f metals (which I cannot name for confidentiality reasons). For pure f metals I have reference values of U and J, and the f states are at the correct position, but in mixed systems the f states tend to alloy, broaden, and end up just below the Fermi level (2 eV instead of 10 eV below), and are relatively insensitive to U. This makes sense if the states are less localized, but still it's strange: experimentally the f peak in these systems is still found at -10 eV... So:

1) is this hybridization physical?
2) has anyone seen this before?
3) is there evidence that U for a surface is different from U for a bulk?
4) is there a way to increase U or something, to force the band to the "correct" position?


Cheers,

Matthieu

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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