[Pw_forum] energy of 33CNT

[lan haiping]

Hi, Zhu Xi

to my knowledge , we always compare workfunctions of nanotubes with
experimental
data, but not fermi level !
In order to check your result, you can follow nicolas's suggestion : using
pp.x to obtain the vacuum level, the difference between fermi level and
vacuum level is workfunction of nanotube.
please note, due to periodic images' interaction, the cell size of your
system will affect the final result you obtain.

Bests,
Hai-Ping


On Jan 10, 2008 6:37 AM, Zhu Xi <ustc0200 at gmail.com> wrote:

> Hi Nicholas,
> thanks for your reply, but to my understaning, the 0.625eV fermi energy is
> wrong, it should be between -5~-4eV, I don't know why the code give such a
> fermi energy.....
>
>
> On 1/10/08, Nicholas E. Singh-Miller <nedward at mit.edu> wrote:
> >
> > Dear Zhu Xi,
> >
> > I have not run your input file, but assuming that it is correct and this
> > 0.625eV is what you read directly from the output, this Fermi energy
> > should also be correct.  If you are interested in the work function of
> > the (3,3)CNT you will have to obtain the difference between a vacuum
> > potential and the Fermi energy.  In short the potential in the vacuum !=
> > 0
> > due to the use of periodic boundary conditions.  If you  use pp.x to
> > obtain the potential remember that is is output in Rydbergs.   This is
> > all
> > discussed other times on the forum.
> >
> > best of luck,
> >
> > Nicholas
> >
> > On Thu, 10 Jan 2008, Zhu Xi wrote:
> >
> > > Dear users,
> > >
> > > I run a scf calculation of (3,3)CNT, but the fermi energy is 0.652eV,
> > can
> > > anyone give some suggestion? thanks
> > >
> > >
> > ====================================================================================
> >
> > >
> > > &control
> > >         calculation='scf',
> > >         PSEUDO_DIR='./',
> > >         prefix='33',
> > >         forc_conv_thr=1.0D-4,
> > > /
> > > &SYSTEM
> > >         ibrav = 0,
> > >          celldm(1)= 18.8972612499,
> > >        nat = 12,
> > >         ntyp = 1,
> > >         ecutwfc = 40.0 ,
> > >         nosym = .true. ,
> > >         nbnd  = 48 ,
> > >   occupations= 'smearing',degauss = 0.001
> > >
> > > /
> > > &electrons
> > >        conv_thr    = 1.D-6,
> > >        mixing_beta = 0.5D0,
> > > /
> > > CELL_PARAMETERS
> > >     1.0    0.000000000    0.000000000
> > >     0.000000000     1.0    0.000000000
> > >     0.000000000    0.000000000     0.245951
> > > ATOMIC_SPECIES
> > >    C    12.00000  C.pz-vbc.UPF
> > > ATOMIC_POSITIONS (crystal)
> > > C        0.625289967   0.669611155   0.250000000
> > > C        0.487077242   0.709466388   0.250000000
> > > C        0.291384631    0.523168925   0.250000000
> > > C        0.374710033   0.330388845   0.750000000
> > > C        0.512922758   0.290533612   0.750000000
> > > C        0.708615369   0.476831075   0.750000000
> > > C        0.416429985   0.692001578    0.750000000
> > > C        0.675464001   0.616817067   0.750000000
> > > C        0.312292454   0.592869751   0.750000000
> > > C        0.583570015   0.307998422   0.250000000
> > > C        0.324535999   0.383182933   0.250000000
> > > C        0.687707546   0.407130249   0.250000000
> > > K_POINTS automatic
> > > 1 1 11 0 0 0
> > >
> > > ==================================================
> > >
> >
> > *****************************************
> > Nicholas E. Singh-Miller
> > Ph.D. Candidate
> > Prof. Marzari Group ( quasiamore.mit.edu)
> > Materials Science and Engineering
> > Massachusetts Institute of Technology
> > 13-4066
> > (617)324-0372
> > *****************************************
> > _______________________________________________
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> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> >
>
>
>
> --
> X
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>


-- 
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping at gmail.com, hplan at pku.edu.cn
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