[Pw_forum] Problem with newly implemented LDA -1/2 in atomic code (ld1)

[Rajan Pandey]

Hi Nicola,

Your comment prompted me to get the reference [ L. G. Ferreira, M. Marques
and L. K. Teles, Phys. Rev. B 78 125116 (2008) ] and try to figure out the
way authors worked out LDA - 1/2 method, in general.
>From what I see quickly in the above paper, that they have done band
structure calculation of several materials using VASP
and SIESTA and obtained the band gaps in excellent agreement with
experiments. So my guess is that they are propagating
the "LDA-1/2" pseudo in the extended system as is.

Hi Layla,

Thanks a lot. I am looking forward to hear from you about the details of
LDA-1/2 in QE-4.3a.

Thanks, and regards,

Rajan

Rajan K. Pandey, Ph.D.

Advisory Research Engineer,
Semiconductor Research & Development Center
India Systems & Technology Engineering Lab
IBM India Pvt. Ltd.
MD3 1F B354
Manyata Embassy  Business Park
Nagawara, Outer Ring Road
Bangalore - 560045, India
Phone: +91-80-28061262
Mobile: +91-9901850981
Email: rajapand at in.ibm.com
            rajanpandey at gmail.com

On Tue, Mar 29, 2011 at 9:17 PM, Layla Martin-Samos
<lmartinsamos at gmail.com>wrote:

> H,
> sometime ago LDA-1/2 in pwscf was working. I saw some numbers for TiO2
> anatase, But I do not remember the details.
>
> i'll ask around
>
> bests regards
>
> Layla
>
>
>
>
> 2011/3/29 Nicola Marzari <nicola.marzari at materials.ox.ac.uk>
>
>>
>>
>> Hi,
>>
>> If I understand correctly, you generated a lda-1/2 pseudo
>> with the atomic code, but did a lda calculation on silicon
>> with pwscf - so you will have gotten very similar but not perfectly
>> identical results, of lda bulk silicon done with a consistent
>> pseudo (lda) or an inconsistent pseudo .
>>
>> 2) not sure if lda-1/2 is in pwscf (I think not) or if it
>> can be applied to solids.
>>
>>                        nicola
>>
>>
>>
>> On 3/29/11 3:28 PM, Rajan Pandey wrote:
>> > Dear Quantum Espresso Community,
>> >
>> > I built the latest release (perhaps alpha) of QE-4.3a. Tried to look
>> > into the latest LDA -1/2 (assumed to be similar to SIC) in atomic code
>> > (ld1), and from the available test case of Silicon,
>> > I decided to check if I get a corrected band gap of bulk Si (from
>> > example05). First I generated LDA - 0.5 pseudo (input deck for the same
>> > is supplied with the distribution). Subsequently,
>> > to run a band structure calculation of Si, I used the template in
>> > example05. First I did band structure calculation with Si.pz-vbc.UPF,
>> > and then another calculation with the LDA - 0.5 pseudo (Si.LDA.0.5.UPF).
>> > I checked the output of scf calculation of the latter (I am copying the
>> > portion from output):
>> >
>> >
>> >       PseudoPot. # 1 for Si read from file Si.LDA.0.5.UPF
>> >       MD5 check sum: ac6493edff0fd6b486246c8fa11d17dc
>> >       Pseudo is Norm-conserving, Zval =  4.0
>> >       Generated using LDA-1/2 implemented by Leonardo Matheus Marion
>> Jorge
>> >       Using radial grid of  431 points,  2 beta functions with:
>> >                  l(1) =   0
>> >                  l(2) =   1
>> >
>> >       atomic species   valence    mass     pseudopotential
>> >          Si             4.00    28.08600     Si( 1.00)
>> >
>> >       48 Sym.Ops. (with inversion)
>> >
>> > However, the end results of the two calculations are the same. That is
>> > the band structure and hence the band gap in two cases are same - nearly
>> > 50% underestimated.
>> > Not sure if I am missing something. I have attached the two scripts:
>> > run_example-0 ==> uses LDA pseudo, and run_example ==> uses LDA - 1/2
>> > pseudo.
>> > I shall appreciate any suggestion.
>> >
>> > Thanks, and regards,
>> >
>> > Rajan
>> >
>> --
>> ----------------------------------------------------------------------
>> Prof Nicola Marzari    Department of Materials    University of Oxford
>> Chair of Materials Modelling  Director, Materials Modelling Laboratory
>> nicola.marzari at materials.ox.ac.uk     http://mml.materials.ox.ac.uk/NM
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>
>
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