[Wien] Fwd: Need advice for modeling the band gap in a charge transfer insulator

[shamik chakrabarti]

Dear wien2k users,

                          In this regard if we receive some more comments
and information over my question on charge transfer insulator, that will be
very helpful for us.



---------- Forwarded message ----------
From: shamik chakrabarti <shamikphy at gmail.com>
Date: Tue, Oct 25, 2011 at 7:04 PM
Subject: Re: [Wien] Need advice for modeling the band gap in a charge
transfer insulator
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>


Dear David,

              Thank you very much for your response and useful information.

Best regards,


2011/10/25 David Tompsett <dat36 at cam.ac.uk>

> Hi Shamik,
>
> DFT+U can sometimes give a reasonable description of materials with some
> charge transfer (possibly also some Mott) insulating character eg. NiO. But
> it seems that in your case itinerant states are important to the band gap
> and in that case using Hybrid functionals that include exchange between all
> states (including itinerant ones) often helps eg. MnO. I think a full hybrid
> functional set will come out in an upcoming version of Wien2k?
>
> Some references:
> Tran et al.
> PHYSICAL REVIEW B 83, 235118 (2011)
>
> Best,
> David.
>
> 2011/10/25 shamik chakrabarti <shamikphy at gmail.com>
>
>>
>> Dear wien2k users,
>>
>>                             We all know that LSDA (or GGA)+U can be used
>> successfully for a Mott-Hubbard insulator. Anisimov et al. [PRL 99, 156404
>> (2007)] have described that for a charge transfer insulator we need to use
>> LDA+DMFT for modelling their band structure properly. Now my question is :
>>
>> (1) Is their any option in wien2k by which we can use LDA+DMFT?
>>
>> (2) In our calculation after applying GGA+U (U for d orbital of TM) we saw
>> that although there are a band gap between spin up & spin dn d DOS of
>> transition metal, there are ligand (O p) DOS at Fermi Energy which is making
>> our material metallic while experimentally it is an insulator [conductivity
>> ~ 10^(-7)]. Here should we apply some value of U (say 0.15 Ry) for O p
>> orbital also?
>>
>> (3) Any other advice regarding to this problem will be highly appreciated.
>>
>> Thanks in advance.
>>
>> yours faithfully,
>> --
>> Shamik Chakrabarti
>> Senior Research Fellow
>> Dept. of Physics & Meteorology
>> Material Processing & Solid State Ionics Lab
>> IIT Kharagpur
>> Kharagpur 721302
>> INDIA
>>
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>>
>>
>
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>


-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA



-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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