[Pw_forum] The symmetry of bands
程迎春
yccheng.nju at gmail.com
Fri Apr 3 14:16:53 CEST 2009
Dear dalcorso,
Thank you for your detailed reply. The initial output I posted is not
consistent with your output because I changed the
"starting_magnetization=0.00," to 0.01. Though the energy is the same, the
symmetry is different. I recalculate it with "starting_magnetization=0.00,"
and the output is same as your output.
In addition, I want to know how to calculate the exciton energy level
? Is that possible in recent pwscf?
2009/4/3 Dal Corso Andrea <dalcorso at sissa.it>
>
> On my PC, with your input I obtain:
>
> &plot nbnd= 30, nks= 1 /
> 0.000000 0.000000 0.000000
> -8.070 -8.070 -5.968 -5.968 1.092 1.092 6.154 6.154 6.169
> 6.169
> 6.802 6.802 6.816 6.816 7.016 7.016 11.136 11.136 13.603
> 13.603
> 17.514 17.514 18.094 18.094 18.118 18.118 19.967 19.967 20.042
> 20.042
>
> That compare quite well with your bands:
>
> &plot nbnd= 30, nks= 1 /
> 0.000000 0.000000 0.000000
> -8.070 -8.070 -5.968 -5.968 1.092 1.092 6.154 6.154 6.169
> 6.169
> 6.803 6.803 6.816 6.816 7.015 7.015 11.136 11.136 13.603
> 13.603
> 17.513 17.513 18.094 18.094 18.118 18.118 19.967 19.967 20.042
> 20.042
>
> The output of bands.x says that the code is using the group C_6v
> to classify the bands
>
> xk=( 0.00000, 0.00000, 0.00000 )
>
> double point group C_6v (6mm)
> there are 9 classes and 3 irreducible representations
> the character table:
>
> E -E C2 2C3 -2C3 2C6 -2C6 3s_v 3s_d
> -C2 -3s_v -3s_d
> G_7 2.00 -2.00 0.00 1.00 -1.00 1.73 -1.73 0.00 0.00
> G_8 2.00 -2.00 0.00 1.00 -1.00 -1.73 1.73 0.00 0.00
> G_9 2.00 -2.00 0.00 -2.00 2.00 0.00 0.00 0.00 0.00
>
> That has only three representations. An actally the .rap file contains
> only 1 2 or 3:
>
> &plot_rap nbnd_rap= 30, nks_rap= 1 /
> 0.000000 0.000000 0.000000 T
> 1 1 2 2 2 2 2 2 3
> 3
> 1 1 3 3 1 1 1 1 2
> 2
> 2 2 1 1 3 3 1 1 2
> 2
>
> So the two bands 11-12 at 6.803 are 1 -> Gamma_7, the two bands 13-14 at
> 6.816 are 3-> \Gamma_9 and
> the two bands 15-16 7.015 are 1 -> \Gamma_7. The splitting is 13 meV and
> 0.199 meV in reasonable agreement with the APL that you mention.
>
> It seems that you have the correct bands but bands.x is not using C_6v
> to classify the bands.
> Which is the output of bands.x?
>
> Andrea
>
>
>
> On Fri, 2009-04-03 at 11:10 +0800, 程迎春 wrote:
> > Dear pwscf users,
> > I calculated band structure of AlN considering spin-orbital
> > interaction. Some published reports showed that considering
> > spin-orbital interaction the top of valence band is split into the
> > Gamma7, Gamma9 and Gamma7 states by crystal field and spin-orbital
> > coupling (Appl. Phys. Lett. 83, 5163). However, my calculated band
> > structure is different from the published one. The following is the
> > input files:
> > scf.in
> > &control
> > title = 2h_aln,
> > prefix = '2h_band',
> > calculation = 'scf' ,
> > restart_mode = 'from_scratch' ,
> > wf_collect = .false. ,
> > outdir = './' ,
> > wfcdir = './' ,
> > pseudo_dir = './' ,
> > tstress = .true. ,
> > tprnfor = .true. ,
> > wf_collect = .true. ,
> > /
> > &SYSTEM
> > ibrav = 4,
> > celldm(1) = 5.904838149212,
> > celldm(3) = 1.603024550651,
> > nat = 4,
> > ntyp = 2,
> > ecutwfc = 80,
> > nosym = .false. ,
> > lspinorb = .true.,
> > noncolin= .true.,
> > starting_magnetization=0.00,
> > /
> > &ELECTRONS
> > electron_maxstep = 100,
> > conv_thr = 1.D-12,
> > /
> > ATOMIC_SPECIES
> > N 14.00700 N.rel-pbe-rrkjus.UPF
> > Al 26.98200 Al.rel-pbe-rrkj.UPF
> > ATOMIC_POSITIONS (crystal)
> > N 0.333333333 0.666666667 0.379371803
> > N 0.666666667 0.333333333 0.879371803
> > Al 0.333333333 0.666666667 -0.002269507
> > Al 0.666666667 0.333333333 0.497730493
> > K_POINTS automatic
> > 4 4 4 1 1 1
> > band.in
> > &control
> > title = 2h_aln,
> > prefix = '2h_band',
> > calculation = 'bands' ,
> > restart_mode = 'from_scratch' ,
> > wf_collect = .false. ,
> > outdir = './' ,
> > wfcdir = './' ,
> > pseudo_dir = './' ,
> > /
> > &SYSTEM
> > ibrav = 4,
> > celldm(1) = 5.904838149212,
> > celldm(3) = 1.603024550651,
> > nat = 4,
> > ntyp = 2,
> > ecutwfc = 80,
> > occupations='fixed',
> > nbnd=30,
> > lspinorb = .true.,
> > noncolin= .true.,
> > starting_magnetization=0.00,
> > /
> > &ELECTRONS
> > electron_maxstep = 100,
> > conv_thr = 1.D-12,
> > /
> > ATOMIC_SPECIES
> > N 14.00700 N.rel-pbe-rrkjus.UPF
> > Al 26.98200 Al.rel-pbe-rrkj.UPF
> > ATOMIC_POSITIONS (crystal)
> > N 0.333333333 0.666666667 0.379371803
> > N 0.666666667 0.333333333 0.879371803
> > Al 0.333333333 0.666666667 -0.002269507
> > Al 0.666666667 0.333333333 0.497730493
> > K_POINTS
> > 1
> > 0.000000 0.000000 0.000000 1.00
> >
> > bands.in for bands.x to get band symmetry information
> >
> > &inputpp
> > prefix='2h_band'
> > outdir='./'
> > filband='spin.dat'
> > lsigma(3)=.true.
> > lsym=.true.
> > /
> > The calculated results of the band structure at Gamma point is as
> > following:
> > spin.dat:
> > &plot nbnd= 30, nks= 1 /
> > 0.000000 0.000000 0.000000
> > -8.070 -8.070 -5.968 -5.968 1.092 1.092 6.154 6.154
> > 6.169 6.169
> > 6.803 6.803 6.816 6.816 7.015 7.015 11.136 11.136
> > 13.603 13.603
> > 17.513 17.513 18.094 18.094 18.118 18.118 19.967 19.967
> > 20.042 20.042
> >
> > spin.dat.rap:
> > &plot_rap nbnd_rap= 30, nks_rap= 1 /
> > 0.000000 0.000000 0.000000 T
> > 1 2 5 6 5 6 5 6
> > 3 4
> > 1 2 3 4 1 2 1 2
> > 5 6
> > 5 6 1 2 3 4 1 2
> > 5 6
> >
> > My questions are:
> > 1. Why the calculated top of valence bands (15th, and 16th ) do not
> > split as reported work (Appl. Phys. Lett.83,5163)?
> > 2. In the spin.dat.rap file, what does the symbol "T" stand for? And
> > what does the "1 2 5 6 5 6 5 ..."
> > mean?
> >
> > Thank you in advance!
> >
> > --
> > Y. C. Cheng
> > Department of Physics
> > Nanjing University
> > Nanjing 210093
> > P. R. China
> > Tel: 86-25-83592907
> > Email: yccheng.nju at gmail.com
> >
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> --
> Andrea Dal Corso Tel. 0039-040-3787428
> SISSA, Via Beirut 2/4 Fax. 0039-040-3787528
> 34014 Trieste (Italy) e-mail: dalcorso at sissa.it
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
--
Y. C. Cheng
Department of Physics
Nanjing University
Nanjing 210093
P. R. China
Tel: 86-25-83592907
Email: yccheng.nju at gmail.com
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