[Pw_forum] very large value 'U' obtained for 'GaAs' by linear response method

[Bramha Pandey]

sorry for wrong matrix copied in previous mail.
CHI0^-1 - CHI^-1 Matrix

    0.0000    0.0000    0.0000
    0.0000    0.0000    0.0000
    0.0000    0.0000    0.0000
  type:            1  U0 =   0.000000000000000E+000

On Sun, Oct 7, 2012 at 10:30 PM, Bramha Pandey <pandey.bramha at gmail.com>wrote:

> Dear Prof. Matteo,
> i am using Ga, pseudo with 3d as a valence, Hubbard_l=2 is set for 'Ga'.
> If it should change how much value i have to set it?
>
> Dear sir i am totally struck by zero matrix element in ch0^-1 - chi^-1, so
> always it gifted me ZERO value where as ch0 and chi matrix are NON ZERO
> with same element value.
> CHI_0 Matrix
>    -0.0002  -0.0002   0.0005
>   -0.0002  -0.0002   0.0005
>    0.0005   0.0005  -0.0010
>    CHI Matrix
>    -0.0002  -0.0002   0.0005
>   -0.0002  -0.0002   0.0005
>    0.0005   0.0005  -0.0010
>
>   CHI0^-1 - CHI^-1 Matrix
>
>     0.0000    0.0000
>     0.0000    0.0000
>   type:            1  U0 =   0.000000000000000E+000
> This above is for all the  2 atoms supercell combination when we take the
> ZB structure with 2 atoms: (1) when both atoms are 'Ga'
> (2) when both atoms are 'Ga1' and 'Ga' (3) when both atoms are different
> 'Ga' and 'As'.
>
> All above three conditions are tested under one atom(Ga1 or Ga) is
> perturbed.
> Please Sir give me some ray of hope so that i can get rid of this
> situation.
>
>
> On Sun, Oct 7, 2012 at 8:10 PM, Matteo Cococcioni <matteo at umn.edu> wrote:
>
>> Dear Bramha,
>>
>> in J. Phys.: Condens. Matter 22 (2010) 055602 we did a similar
>> calculation but we got pretty different numbers (see Table 2 of the
>> reference). Maybe the states of Ga you applied U or alpha to are
>> completely full. what is the value of l set for Ga in set_hubbard_l ?
>> did you change that? also, for Ga, you better use a pseudo with 3d
>> states in the valence rather than frozen in the core.
>>
>> Matteo
>>
>>
>>
>> On Sun, Oct 7, 2012 at 7:31 AM, Bramha Pandey <pandey.bramha at gmail.com>
>> wrote:
>> > First of all thank you very much Dear Prof.Stefano.
>> > I have change the input as ZB 'GaAs' structure and calculate the 'U'
>> value
>> > for both 'Ga' and 'As' which is given bellow.
>> > But i wondered to see the 'U' value of 'Ga' 1010.79 which is quite
>> large so
>> > how can i figure out this is  correct or wrong?
>> > No of Atom        U_Ga                       U_As
>> > 2                1043.35792360332    2.87817590827985
>> > 16              1010.81003743078    2.82970777976411
>> > 54              1010.79529573193    2.82968584264055
>> > 128             1010.79528904780    2.82968583269392
>> > 250             1010.79528904476    2.82968583268940
>> > Any comment is welcome.
>> > --
>> > Thanks and Regards
>> > Bramha Prasad Pandey
>> > Ph.D Student Indian School of Mines(ISM)
>> > Dhanbad, INDIA.
>> >
>> >
>> > _______________________________________________
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>>
>>
>>
>> --
>> Matteo Cococcioni
>> Department of Chemical Engineering and Materials Science,
>> University of Minnesota
>> 421 Washington Av. SE
>> Minneapolis, MN 55455
>> Tel. +1 612 624 9056    Fax +1 612 626 7246
>> _______________________________________________
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>>
>
>
>
> --
> Thanks and Regards
> Bramha Prasad Pandey
> Ph.D Student Indian School of Mines(ISM)
> Dhanbad, INDIA.
>
>


-- 
Thanks and Regards
Bramha Prasad Pandey
Ph.D Student Indian School of Mines(ISM)
Dhanbad, INDIA.
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