[Wien] A basic question about GGA+U approach

[Shamik Chakrabarti]

Dear Haranath Ghosh,

         Yes U can be used for p orbital of oxygen...but what value of U
you are going to use that depends on the system and the problem you are
studied.....& also what error you are getting??...that is not clear from
your mail

with regards,

On Tue, Jun 26, 2012 at 6:48 PM, Haranath Ghosh <ghoshharanath at yahoo.com>wrote:

> Dear experienced Users and developer Wien2k,
>
>  Is it possible to use U value for Oxygens with l=1 orbitals. I always get
> error. Thanks for your response.
>
> with best regards, Haranath Ghosh
>
> --- On *Tue, 6/26/12, shamik chakrabarti <shamikphy at gmail.com>* wrote:
>
>
> From: shamik chakrabarti <shamikphy at gmail.com>
> Subject: Re: [Wien] A basic question about GGA+U approach
> To: "A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at>
> Date: Tuesday, June 26, 2012, 6:37 PM
>
>
> Dear Prof. Peter Blaha,
>
>             Thank you very much for your reply. I got my answer.
>
> with best regards,
>
> On Tue, Jun 26, 2012 at 11:19 AM, Peter Blaha <
> pblaha at theochem.tuwien.ac.at<http://us.mc1606.mail.yahoo.com/mc/compose?to=pblaha@theochem.tuwien.ac.at>
> > wrote:
>
> Yes, U depends on the type of atom, but of course also on the specific
> compound.
> For metallic Fe the U should be in the range of 0-2 eV at most, for some
> insulating compound with very localized states, it may go up to even 4-6
> (maybe even 8) eV.
>
> Am 26.06.2012 06:42, schrieb shamik chakrabarti:
>
> Dear wien2k users,
>
>        We generally choose the value of U by fitting it with
> experimental band gap or by calculating it through linear response
> method. Now my question is that whether U is element specific or depends
> on the composite in which the element reside? (*if I consider same
>
> magnetic configuration for all the composites I am referring here...as
> antiferromagntism do produce a band gap even without applying any U*)
>
>
> To make it more clear, say for Fe d, I have seen in literature, people
> have used U=4.5 to 5 eV......in some of our calculation we have even
> used U=6 eV for Fe d to obtain better electronic structure having closer
> match with experimental observation. Hence it looks that U for Fe d
> orbital can have value ranging from 4.5-6 eV...& that mean U is not
> element specific rather it depends on the composite in which the element
> exist (I again want to insist that if I consider same magnetic
> configuration for all the composites). Am I right?
>
> with regards,
>
> --
> Shamik Chakrabarti
> Senior Research Fellow
> Dept. of Physics & Meteorology
> Material Processing & Solid State Ionics Lab
> IIT Kharagpur
> Kharagpur 721302
> INDIA
>
>
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>
>
> --
> Peter Blaha
> Inst.Materials Chemistry
> TU Vienna
> Getreidemarkt 9
> A-1060 Vienna
> Austria
> +43-1-5880115671
>
>
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>
>
>
>
> --
> Shamik Chakrabarti
> Senior Research Fellow
> Dept. of Physics & Meteorology
> Material Processing & Solid State Ionics Lab
> IIT Kharagpur
> Kharagpur 721302
> INDIA
>
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-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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