Dear Layla,
Thank you for your answer, normally if we change (nat = 2, ibrav = 2) to (nat =
8, ibrav = 1),we find the same nature of gap.
If such we have the composition B0.25Ga0.75N how we can determine the nature of
gap?
bests
Said Asma
________________________________
De?: Layla Martin-Samos <lmartinsamos at gmail.com>
??: Said Asma <saidasma1987 at yahoo.fr>
Cc?: "pw_forum at pwscf.org" <pw_forum at pwscf.org>
Envoy? le : Mercredi 18 avril 2012 15h45
Objet?: Re: [Pw_forum] (no subject)
Dear Said, it is not a problem, I think, as increasing the number of atoms will
fold the Brillouin zone into gamma.
bests
Layla
2012/4/18 Said Asma <saidasma1987 at yahoo.fr>
>
>Dear PWScf Users,
>
>I did the band structure of?BN(zinc blende) with two atoms and I found
>aindirectgap? (like literature) Gamma-X. But when I did it with 8 atoms I
>found direct gap Gamma -Gamma.
>
>Why such a problem occurs?
>
>My input files is as following:
>?
>?*With TWO ATOMS:
>
>cat > bn.band.in << EOF
>?&control
>??? calculation='bands'
>??? pseudo_dir = '$PSEUDO_DIR/',
>??? outdir='$TMP_DIR/',
>??? prefix='bn'
>?/
>?&system
>??? ibrav=? 2, celldm(1) = 6.76, nat=? 2, ntyp= 2,
>??? ecutwfc = 60.0,
>??? occupations ='smearing',
>??? smearing = 'methfessel-paxton',
>??? degauss= 0.03,
>?/
>?&electrons
>???????????????? conv_thr = 1.0d-7 ,
>???????????????? mixing_mode = 'plain' ,
>???????????????? mixing_beta = 0.2
,
>???????????????? diagonalization = 'david' ,
>?/
>ATOMIC_SPECIES
>?B? 10.811? B.pz-vbc.UPF
>?N? 14.007? N.pz-vbc.UPF
>ATOMIC_POSITIONS
>? B 0.00 0.00 0.00
>? N 0.25 0.25 0.25
>K_POINTS {crystal_b}
>5
>0.5? 0.5? 0.5? 400
>0??? 0??? 0??? 400
>1.0? 0??? 0??? 400
>0.75 0.75 0??? 400
>0??? 0??? 0??? 400
>EOF
>$ECHO "? running the band-structure calculation for bn...\c"
>$PW_COMMAND < bn.band.in > bn.band.out
>check_failure $?
>$ECHO " done"
>
>
>
>*and WITH 8 ATOMS:
>
>cat > bn.band.in << EOF
>?&control
>??? calculation='bands'
>??? pseudo_dir = '$PSEUDO_DIR/',
>??? outdir='$TMP_DIR/',
>??? prefix='bn'
>?/
>?&system
>??? ibrav= 1, celldm(1) = 6.82, nat=8, ntyp= 2,
>??? ecutwfc = 40.0, nbnd = 40,
>??? occupations ='smearing',
>??? smearing = 'methfessel-paxton',
>??? degauss= 0.02,
>?/
>?&electrons
>? conv_thr =? 1.0d-7,
>??? mixing_beta = 0.2,
>?/
>
>ATOMIC_SPECIES
>?B? 10.811? B.pz-vbc.UPF
>?N? 14.007? N.pz-vbc.UPF
>ATOMIC_POSITIONS
>?B????? 0.000???? 0.000???? 0.000
>?N????? 0.250???? 0.250???? 0.250
>?B????? 0.000???? 0.500???? 0.500
>?N????? 0.250???? 0.750???? 0.750
>?B????? 0.500???? 0.500???? 0.000
>?N????? 0.750???? 0.250???? 0.750
>?B????? 0.500???? 0.000???? 0.500
>?N????? 0.750???? 0.750???? 0.250
>
>K_POINTS {crystal_b}
>4
>0??? 0??? 0??? 40
>0.5? 0??? 0??? 40
>0.5? 0.5? 0??? 40
>0??? 0??? 0??? 40
>EOF
>$ECHO "? running the band-structure calculation for bn...\c"
>$PW_COMMAND < bn.band.in > bn.band.out
>check_failure $?
>$ECHO " done"
>
>Any help would be appreciated.
>Best regards,
>Said Asma
>
>
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