Effect of polaron formation on electronic, charge and magnetic properties of Nb12O29

• We present the ab initio study of different phases of Nb12O29, which has been done in the framework of density functional theory using the onsite Hubbard-U correction applied to the Nb-d states. We vary the U parameter in between 0 and 7 eV and suggest U = 3.7-5.0 eV to be most appropriate for the description of Nb12O29. We show that one cannot get any adequate description of this oxide using the crystallographic unit cell but at least 3 times larger supercell is needed increased along the shortest lattice parameter b to accommodate lattice distortions associated with polaron formation. Our results obtained for the enlarged cells show the possibility of simultaneous co-existence of localized states (polaron formation) and delocalized states providing metal-like properties of Nb12O29, in qualitative agreement with available experimental data.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

Nyckelord

Substoichiometric niobium oxides

Polaron

Charge and magnetic ordering

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