Dear Brahma,<div><br></div><div>Ga has a full d-shell. Therefore, if you try to perturb the d-shell of Ga, you can reduce the number of electrons localized on d-states by a positive Hubbard_alpha but there is no way to increase their occupations with a negative Hubbard_alpha. Therefore, the response matrices will be non-linear and you will get very small numbers in them. When you invert these matrices, very large numbers will appear.</div>
<div><br></div><div>Calculating U for full d-shells is not easy, and there is no simple solution (Another known example is ZnO). My personal opinion is that the use of LDA+U is questionable for filled d-shells. In fact if you check the paper mentioned by Matteo, the gap for GaAs is corrected by applying U and V (inter-site interactions) on Ga-p states and states which overlap with Ga-p. No correction on Ga-d is applied.</div>
<div><br></div><div>Best regards,</div><div><br></div><div>Burak<br><br><div class="gmail_quote">On Sun, Oct 7, 2012 at 12:02 PM, Bramha Pandey <span dir="ltr"><<a href="mailto:pandey.bramha@gmail.com" target="_blank">pandey.bramha@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">sorry for wrong matrix copied in previous mail.<div class="im"><br>CHI0^-1 - CHI^-1 Matrix <br> <br> 0.0000 0.0000 0.0000<br>
</div> 0.0000 0.0000 0.0000<div class="im HOEnZb"><br> 0.0000 0.0000 0.0000<br> type: 1 U0 = 0.000000000000000E+000<br>
<br></div><div class="HOEnZb"><div class="h5"><div class="gmail_quote">On Sun, Oct 7, 2012 at 10:30 PM, Bramha Pandey <span dir="ltr"><<a href="mailto:pandey.bramha@gmail.com" target="_blank">pandey.bramha@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear Prof. Matteo,<br>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?<br><br>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.<br>
CHI_0 Matrix <br> -0.0002 -0.0002 0.0005<br> -0.0002 -0.0002 0.0005<br> 0.0005 0.0005 -0.0010<br> CHI Matrix <br> -0.0002 -0.0002 0.0005<br> -0.0002 -0.0002 0.0005<br> 0.0005 0.0005 -0.0010<br>
<br> CHI0^-1 - CHI^-1 Matrix <br> <br> 0.0000 0.0000<br> 0.0000 0.0000<br> type: 1 U0 = 0.000000000000000E+000<br>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'<br>
(2) when both atoms are 'Ga1' and 'Ga' (3) when both atoms are different 'Ga' and 'As'.<br><br>All above three conditions are tested under one atom(Ga1 or Ga) is perturbed.<br>Please Sir give me some ray of hope so that i can get rid of this situation.<div>
<div><br>
<br><div class="gmail_quote">On Sun, Oct 7, 2012 at 8:10 PM, Matteo Cococcioni <span dir="ltr"><<a href="mailto:matteo@umn.edu" target="_blank">matteo@umn.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear Bramha,<br>
<br>
in J. Phys.: Condens. Matter 22 (2010) 055602 we did a similar<br>
calculation but we got pretty different numbers (see Table 2 of the<br>
reference). Maybe the states of Ga you applied U or alpha to are<br>
completely full. what is the value of l set for Ga in set_hubbard_l ?<br>
did you change that? also, for Ga, you better use a pseudo with 3d<br>
states in the valence rather than frozen in the core.<br>
<br>
Matteo<br>
<div><div><br>
<br>
<br>
On Sun, Oct 7, 2012 at 7:31 AM, Bramha Pandey <<a href="mailto:pandey.bramha@gmail.com" target="_blank">pandey.bramha@gmail.com</a>> wrote:<br>
> First of all thank you very much Dear Prof.Stefano.<br>
> I have change the input as ZB 'GaAs' structure and calculate the 'U' value<br>
> for both 'Ga' and 'As' which is given bellow.<br>
> But i wondered to see the 'U' value of 'Ga' 1010.79 which is quite large so<br>
> how can i figure out this is correct or wrong?<br>
> No of Atom U_Ga U_As<br>
> 2 1043.35792360332 2.87817590827985<br>
> 16 1010.81003743078 2.82970777976411<br>
> 54 1010.79529573193 2.82968584264055<br>
> 128 1010.79528904780 2.82968583269392<br>
> 250 1010.79528904476 2.82968583268940<br>
> Any comment is welcome.<br>
> --<br>
> Thanks and Regards<br>
> Bramha Prasad Pandey<br>
> Ph.D Student Indian School of Mines(ISM)<br>
> Dhanbad, INDIA.<br>
><br>
><br>
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<br>
--<br>
Matteo Cococcioni<br>
Department of Chemical Engineering and Materials Science,<br>
University of Minnesota<br>
421 Washington Av. SE<br>
Minneapolis, MN 55455<br>
Tel. <a href="tel:%2B1%20612%20624%209056" value="+16126249056" target="_blank">+1 612 624 9056</a> Fax <a href="tel:%2B1%20612%20626%207246" value="+16126267246" target="_blank">+1 612 626 7246</a><br>
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</font></span></blockquote></div><br><br clear="all"><br>-- <br>Thanks and Regards<br>Bramha Prasad Pandey<br>Ph.D Student Indian School of Mines(ISM)<br>Dhanbad, INDIA.<br><br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>Thanks and Regards<br>Bramha Prasad Pandey<br>Ph.D Student Indian School of Mines(ISM)<br>Dhanbad, INDIA.<br><br>
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