Dear Muthu, the Brillouin zone of your supercell is 1/2 x 1/2 x 1/2 times the original Brillouin zone and the bands of the unit cell are now *folded* in the new (smaller) Brillouin zone.
Hope this helps. Bests, Pietro Bonfa' On 01/22/2014 07:13 PM, Muthu V wrote: > Dear QE users > > > i have run band structure calculation for Si unit cell and 2x2x2 > super-cell. as far as i know the both band structure should be same > since 2x2x2 super-cell is = simply repeating unit cell in space twice > all direction. > > but here i have different band structures and do not know why this > occurs. below i attached input of Si unit & 2x2x2 supercell. > > *_input for Si 2x2x2 supercell_* > # self-consistent calculation > cat > si.scf.in <http://si.scf.in> << EOF > &control > calculation='scf' > restart_mode='from_scratch', > prefix='si' > pseudo_dir = '/home/physics/Desktop/espresso-5.0.1/pseudo/', > outdir='/home/physics/tmp/' > / > &system > ibrav = 2, > A = 10.7952 , > B = 10.7952 , > C = 10.7952 , > cosAB = 0 , > cosAC = 0 , > cosBC = 0 , > nat = 16, > ntyp = 1, > ecutwfc = 18.0 , > ecutrho = 72 , > occupations = 'smearing' , > degauss = 0.01 , > smearing = 'gaussian' , > > / > &ELECTRONS > conv_thr = 1.0d-6, > mixing_beta = 0.3, > / > ATOMIC_SPECIES > Si 28.08600 Si.pz-mt_fhi.UPF > ATOMIC_POSITIONS angstrom > Si 0.000000000 0.000000000 0.000000000 > Si 1.349401350 1.349401350 1.349401350 > Si -2.698802700 2.698802700 0.000000000 > Si -1.349401350 4.048204050 1.349401350 > Si 0.000000000 2.698802700 2.698802700 > Si 1.349401350 4.048204050 4.048204050 > Si -2.698802700 5.397605400 2.698802700 > Si -1.349401350 6.747006750 4.048204050 > Si -2.698802700 0.000000000 2.698802700 > Si -1.349401350 1.349401350 4.048204050 > Si -5.397605400 2.698802700 2.698802700 > Si -4.048204050 4.048204050 4.048204050 > Si -2.698802700 2.698802700 5.397605400 > Si -1.349401350 4.048204050 6.747006750 > Si -5.397605400 5.397605400 5.397605400 > Si -4.048204050 6.747006750 6.747006750 > K_POINTS automatic > 2 2 2 0 0 0 > EOF > > # band structure calculation along high-symmetry lines > cat > si.band.in <http://si.band.in> << EOF > &control > calculation='bands' > pseudo_dir = '/home/physics/Desktop/espresso-5.0.1/pseudo/', > outdir='/home/physics/tmp/', > prefix='si' > / > &system > ibrav = 2, > A = 10.7952 , > B = 10.7952 , > C = 10.7952 , > cosAB = 0 , > cosAC = 0 , > cosBC = 0 , > nat = 16, > ntyp = 1, > ecutwfc = 18.0 , > ecutrho = 72 , > occupations = 'smearing' , > degauss = 0.01 , > smearing = 'gaussian' , > nbnd = 50, > / > &ELECTRONS > conv_thr = 1.0d-6 , > mixing_beta = 0.3 , > / > ATOMIC_SPECIES > Si 28.08600 Si.pz-mt_fhi.UPF > ATOMIC_POSITIONS angstrom > Si 0.000000000 0.000000000 0.000000000 > Si 1.349401350 1.349401350 1.349401350 > Si -2.698802700 2.698802700 0.000000000 > Si -1.349401350 4.048204050 1.349401350 > Si 0.000000000 2.698802700 2.698802700 > Si 1.349401350 4.048204050 4.048204050 > Si -2.698802700 5.397605400 2.698802700 > Si -1.349401350 6.747006750 4.048204050 > Si -2.698802700 0.000000000 2.698802700 > Si -1.349401350 1.349401350 4.048204050 > Si -5.397605400 2.698802700 2.698802700 > Si -4.048204050 4.048204050 4.048204050 > Si -2.698802700 2.698802700 5.397605400 > Si -1.349401350 4.048204050 6.747006750 > Si -5.397605400 5.397605400 5.397605400 > Si -4.048204050 6.747006750 6.747006750 > K_POINTS > 36 > 0.5 0.5 0.5 1 > 0.4 0.4 0.4 2 > 0.3 0.3 0.3 3 > 0.2 0.2 0.2 4 > 0.1 0.1 0.1 5 > 0.0 0.0 0.0 6 > 0.0 0.0 0.1 7 > 0.0 0.0 0.2 8 > 0.0 0.0 0.3 9 > 0.0 0.0 0.4 10 > 0.0 0.0 0.5 11 > 0.0 0.0 0.6 12 > 0.0 0.0 0.7 13 > 0.0 0.0 0.8 14 > 0.0 0.0 0.9 15 > 0.0 0.0 1.0 16 > 0.0 0.1 1.0 17 > 0.0 0.2 1.0 18 > 0.0 0.3 1.0 19 > 0.0 0.4 1.0 20 > 0.0 0.5 1.0 21 > 0.0 0.6 1.0 22 > 0.0 0.7 1.0 23 > 0.0 0.8 1.0 24 > 0.0 0.9 1.0 25 > 0.0 1.0 1.0 26 > 0.0 0.9 0.9 27 > 0.0 0.8 0.8 28 > 0.0 0.7 0.7 29 > 0.0 0.6 0.6 30 > 0.0 0.5 0.5 31 > 0.0 0.4 0.4 32 > 0.0 0.3 0.3 33 > 0.0 0.2 0.2 34 > 0.0 0.1 0.1 35 > 0.0 0.0 0.0 36 > EOF > > __ > *_Si Unitcell:_* > # self-consistent calculation > cat > si.scf.in <http://si.scf.in> << EOF > &control > calculation='scf' > restart_mode='from_scratch', > prefix='si' > pseudo_dir = '$PSEUDO_DIR/', > outdir='$TMP_DIR/' > / > &system > ibrav= 2, > A = 5.397, > B =5.397, > C = 5.397, > cosAB = 0 , > cosAC = 0 , > cosBC = 0 , nat= 2, ntyp= 1, > ecutwfc =18.0, occupations = 'smearing', degauss = 0.01 smearing > = 'gaussian' , > / > &electrons > conv_thr = 1.0d-6 > mixing_beta = 0.3 > / > ATOMIC_SPECIES > Si 28.086 Si.pz-vbc.UPF > ATOMIC_POSITIONS angstrom > Si 0.0000000000 0.0000000000 0.0000000000 > Si 1.3494013500 1.3494013500 1.3494013500 > K_POINTS automatic > 6 6 6 0 0 0 > EOF > > # band structure calculation along high-symmetry lines > cat > si.band.in <http://si.band.in> << EOF > &control > calculation='bands' > pseudo_dir = '$PSEUDO_DIR/', > outdir='$TMP_DIR/', > prefix='si' > / > &system > ibrav= 2, > A = 5.397, > B =5.397, > C = 5.397, > cosAB = 0 , > cosAC = 0 , > cosBC = 0 , > nat= 2, ntyp= 1, > ecutwfc =18.0, nbnd = 28, > / > &electrons > / > ATOMIC_SPECIES > Si 28.086 Si.pz-vbc.UPF > ATOMIC_POSITIONS angstrom > Si 0.0000000000 0.0000000000 0.0000000000 > Si 1.3494013500 1.3494013500 1.3494013500 > K_POINTS > 36 > 0.5 0.5 0.5 1 > 0.4 0.4 0.4 2 > 0.3 0.3 0.3 3 > 0.2 0.2 0.2 4 > 0.1 0.1 0.1 5 > 0.0 0.0 0.0 6 > 0.0 0.0 0.1 7 > 0.0 0.0 0.2 8 > 0.0 0.0 0.3 9 > 0.0 0.0 0.4 10 > 0.0 0.0 0.5 11 > 0.0 0.0 0.6 12 > 0.0 0.0 0.7 13 > 0.0 0.0 0.8 14 > 0.0 0.0 0.9 15 > 0.0 0.0 1.0 16 > 0.0 0.1 1.0 17 > 0.0 0.2 1.0 18 > 0.0 0.3 1.0 19 > 0.0 0.4 1.0 20 > 0.0 0.5 1.0 21 > 0.0 0.6 1.0 22 > 0.0 0.7 1.0 23 > 0.0 0.8 1.0 24 > 0.0 0.9 1.0 25 > 0.0 1.0 1.0 26 > 0.0 0.9 0.9 27 > 0.0 0.8 0.8 28 > 0.0 0.7 0.7 29 > 0.0 0.6 0.6 30 > 0.0 0.5 0.5 31 > 0.0 0.4 0.4 32 > 0.0 0.3 0.3 33 > 0.0 0.2 0.2 34 > 0.0 0.1 0.1 35 > 0.0 0.0 0.0 36 > EOF > > *thank you > * > > /*_________________________ > *//* > Muthu.V > Madurai Kamaraj Universit**y**/* > */__________________________ > */ > /**/ > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -- Pietro Bonfa' - PhD student Dipartimento di Fisica e Scienze della Terra "Macedonio Melloni" Viale delle Scienze 7A 43124 Parma - Italy
