"**Suspected SPAM**" Re: [Pw_forum] Does anyone know the Hubbard U parameter of InN ?

[Malgorzata Wierzbowska]

On Wed, 11 Apr 2007, ³¯ ¤ÖµØ wrote:

> Dear Matteo and ohters,
>
> Thanks for your suggestion.
>
> I had calculated the bandstructure of InN by LDA .But
> there is no band gap show up.Someone told me the LDA+U
> method could open the gap.That is why I ask this
> question.
>
> Best Regards
> max

  Yes someone (see the abstract below) said this. But I tried
  for ZnX (X=S,Se,Te) series - moving d-states of Zn into their
  experimental position (U was chosen by "numerical experiment") --
  and I did not find much effect on the gap...... Maybe it depends
  also on implementation and the projectors for LDA+U.

  To open a gap you may try to correct pseudopotentials using
  "scissors" operator (see the second paper and citations of that paper).
  Gosia
----------------------------------------------------------
  Title: Effects of cation d states on the structural and electronic 
properties of III-nitride and II-oxide wide-band-gap semiconductors
Author(s): Janotti A, Segev D, Van de Walle CG
Source: PHYSICAL REVIEW B 74 (4): Art. No. 045202 JUL 2006
Document Type: Article
Language: English
Cited References: 54      Times Cited: 1      Find Related Records 
Information
Abstract: Using first-principles methods based on density functional 
theory within the local density approximation (LDA) we calculate the 
structural and electronic properties of wurtzite MgO, ZnO, and CdO, and 
discuss their similarities and dissimilarities with the corresponding 
Group-III nitrides AlN, GaN, and InN. We treat the semicore d states of 
Zn, Cd, Ga, and In explicitly as valence states in a pseudopotential 
approach, investigate the effects of including on-site Coulomb interaction 
for Zn, Cd, Ga, and In semicore d states within the LDA+U method, and 
propose a novel approach to calculate the parameter U. Our results show 
that the LDA+U approach systematically improves the LDA band gap by 
indirectly acting on both the valence-band maximum and conduction-band 
minimum. We also discuss the effects of the on-site Coulomb interaction on 
structural parameters and absolute deformation potentials of ZnO, CdO, 
GaN, and InN.
-----------------------------------------------------------------------
Electronic structure of GaAs under strain

PRB vol 30 p.5753 (1984)

Results of self-consistent relativistic band calculations for GaAs under 
hydrostatic as well as uniaxial strain are presented. Deformation 
potentials related to the splitting of the valence-band edge (Γ15v) are 
calculated with and without inclusion of spin-orbit coupling. The 
trigonal-shear deformation potentials that agree with experiments 
correspond to an internal-strain parameter ζ=0.6±0.1. The calculated 
values, 16-19 eV, of the optical deformation potential d0 are 
substantially smaller than the published experimental results (≃41 eV). 
The E0 gap obtained in the local-density approximation is 0.25 eV. A 
method of correcting for this error and for calculating, 
self-consistently, the lowest s-like conduction band is described, and 
used to derive pressure dependences of the gaps and conduction-band 
masses. The parameters for this adjustment of the conduction band are 
determined for zero pressure, and can be kept pressure independent. We 
find (1/mc*)dmc*/dP=0.68×10-2 kbar-1. The pressure at which 
conduction-band inversion occurs is 30.5 kbar. The value calculated for 
shear deformation potential E2L is 19 eV for ζ=0.6. The 
spin-orbit-induced splitting of the lowest conduction band for 
k→∥[110] and the additional strain-induced splitting are calculated 
and related to experimental results for spin relaxation of photoexcited 
electrons.
-------------------------------------------------------------------------



> --- Matteo Cococcioni <matteo at umn.edu> »¡¡G
>
>>
>> Dear Max,
>>
>> yes, it's quite "unusual" to use LDA+U on atoms like
>> In and N. Usually
>> LDA+U is used with elements having open d or f
>> shells.
>>
>> Anyway this is still possible. To do that you have
>> to add some
>> information in the code regarding the species you
>> want to apply the
>> LDA+U to.
>> In particular you have to modify tabd.f90 and enter
>> the number of
>> electrons initially located on the "Hubbard"
>> electronic states and
>> set_hubbard_l.f90 to tell the code which l channel
>> of the
>> pseudopotential is going to be treated as Hubbard.
>> For example Fe has 6
>> electrons on the d shell; so I will write that
>> hubbard_l = 2 (d states)
>> and initial occupation is 6.
>>
>> To compute U you can apply the procedure introduced
>> in PRB 71 35105 (2005).
>>
>> Hope this helps.
>>
>> Matteo
>>
>>
>> Stefano Baroni wrote:
>>> For God's sake, why would you ever want to use
>> LDA+U for InN?
>>> S.
>>>
>>> On Apr 10, 2007, at 8:18 PM, ³¯ ¤ÖµØ wrote:
>>>
>>>> Dear members,
>>>>
>>>> I am trying to calculate InN by LDA+U
>>>> method(example25).
>>>> Does anyone know the Hubbard U parameter of InN ?
>>>> Thanks.
>>>>
>>>> max
>>>>
>>>>
>>>>
>>>>
>>>>
>>
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