[Pw_forum] how to get U in DFT+Hubbard U

Chao Cao cao at qtp.ufl.edu
Wed Oct 17 21:42:13 CEST 2007

Based on what Matteo told me in his reply, I would guess you should use
two different values...

And they are not even equivalent in my opinion... Anyway, I'm also a
newbie on LDA+U, let's listen to what pro says... :)

Chao Cao

Agostino Migliore wrote:
> Hello
> I am working on electron transfer in a solvated Fe2+/Fe3+ system. The
> electron is (or "should be") always (i.e. for each water configuration)
> essentially localized on one site, but a small portion (increasing near
> the transition state) must be on the other site, just because of a nonzero
> (although small) electronic coupling between the two sites. So, I wonder
> and ask
> if I should use two different U numbers for the two ions (e.g., that
> obtained for the isolated oxidized (3+) site and the one for the reduced
> site (2+), after check, without U, about the site that should turn out to
> be essentially reduced/oxidized) or if I should use an average U for both
> (neglecting the differences due to different water arrangements) and
> "leave the transferring electron to reach its state", without biasing its
> localization through different U's.
> Regards,
> Agostino Migliore
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Chao Cao

Quantum Theory Project and Department of Physics
University of Florida, Gainesville, FL 32611

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