<div>Dear PWscf users,</div>
<div> In my recent calculation of 4H-AlN (ABCB stacking sequence), the band symmetry seems to be missed in bands.x calculation. The output of bands.x is as following:</div>
<div> **************************************************************************</div>
<div> xk=( 0.00000, 0.00000, 0.00000 )</div>
<div> double point group C_6v (6mm)<br> there are 9 classes and 3 irreducible representations<br> the character table:</div>
<div> E -E C2 2C3 -2C3 2C6 -2C6 3s_v 3s_d<br> -C2 -3s_v -3s_d<br>G_7 2.00 -2.00 0.00 1.00 -1.00 1.73 -1.73 0.00 0.00<br>G_8 2.00 -2.00 0.00 1.00 -1.00 -1.73 1.73 0.00 0.00<br>
G_9 2.00 -2.00 0.00 -2.00 2.00 0.00 0.00 0.00 0.00</div>
<div> the symmetry operations in each class:<br> E 1<br> C2 -C2 2 -2<br> 2C6 3 4<br> 2C3 5 6<br> 3s_v-3s_v 7 -7 9 10 -10 -9<br> 3s_d-3s_d 8 -8 12 -11 11 -12<br>
-E -1<br> -2C6 -3 -4<br> -2C3 -5 -6</div>
<div> Band symmetry, C_6v (6mm) double point group:</div>
<div> e( 1 - 2) = -8.01764 eV 2 --> ?<br> e( 3 - 4) = -7.17573 eV 2 --> ?<br> e( 5 - 6) = -7.13551 eV 2 --> ?<br> e( 7 - 8) = -5.93881 eV 2 --> ?<br>
e( 9 - 10) = 1.12077 eV 2 --> G_7<br> e( 9 - 10) = 1.12077 eV 2 --> 0 G_8<br> e( 11 - 12) = 3.70317 eV 2 --> 0 G_7<br> e( 11 - 12) = 3.70317 eV 2 --> G_8<br>
e( 13 - 14) = 3.76782 eV 2 --> ?<br> e( 15 - 16) = 6.34352 eV 2 --> ?<br> e( 17 - 18) = 6.35869 eV 2 --> G_9<br> e( 19 - 20) = 6.58061 eV 2 --> ?<br>
e( 21 - 22) = 6.59473 eV 2 --> G_9<br> e( 23 - 24) = 6.65103 eV 2 --> ?<br> e( 25 - 26) = 6.66500 eV 2 --> G_9<br> e( 27 - 28) = 6.91040 eV 2 --> ?<br>
e( 29 - 30) = 6.92400 eV 2 --> G_9<br> e( 31 - 32) = 7.00967 eV 2 --> G_7<br> e( 31 - 32) = 7.00967 eV 2 --> 0 G_8<br> e( 33 - 34) = 11.19288 eV 2 --> ?<br>
e( 35 - 36) = 13.31415 eV 2 --> ?<br> e( 37 - 38) = 13.59769 eV 2 --> ?<br> e( 39 - 40) = 14.02975 eV 2 --> ?<br> e( 41 - 42) = 17.15974 eV 2 --> ?<br>
e( 43 - 44) = 17.32327 eV 2 --> ?<br> e( 45 - 46) = 17.92003 eV 2 --> ?</div>
<div> **************************************************************************<br>My question are :</div>
<div>1. what does "?" mean in " e( 1 - 2) = -8.01764 eV 2 --> ?" ?</div>
<div>2. what does "0" mean in " e( 9 - 10) = 1.12077 eV 2 --> 0 G_8" ?</div>
<div>3. In 2H-AlN(AB stacking sequence), all the symmetries of bands are shown. Why in 4H-AlN, it seems much more complicated.</div>
<div> </div>
<div>The input files about 4H-AlN for pw.x and bands.x are as following:</div>
<div><a href="http://scf.in">scf.in</a></div>
<div>&control<br> title = 2h_aln,<br> prefix = '4h_band',<br> calculation = 'scf' ,<br> restart_mode = 'from_scratch' ,<br>
wf_collect = .false. ,<br> outdir = './' ,<br> wfcdir = './' ,<br> pseudo_dir = './' ,<br> tstress = .true. ,<br>
tprnfor = .true. ,<br> wf_collect = .true. ,<br> /<br> &SYSTEM<br> ibrav = 4,<br> celldm(1) = 5.866002785691,<br> celldm(3) = 3.238615289089,<br>
nat = 8,<br> ntyp = 2,<br> ecutwfc = 80,<br> nbnd = 46,<br> nosym = .false. ,<br> lspinorb = .true.,<br>
noncolin= .true.,<br> starting_magnetization=0.00,<br> /<br> &ELECTRONS<br> electron_maxstep = 100,<br> conv_thr = 1.D-10,</div>
<div> /<br>ATOMIC_SPECIES<br> N 14.00700 N.rel-pbe-rrkjus.UPF<br> Al 26.98200 Al.rel-pbe-rrkj.UPF<br>ATOMIC_POSITIONS (crystal)<br>N 0.000000000 0.000000000 -0.000722968<br>N 0.000000000 0.000000000 0.499277032<br>
N 0.333333333 0.666666667 0.249293699<br>N 0.666666667 0.333333333 0.749293699<br>Al 0.000000000 0.000000000 0.188800277<br>Al 0.000000000 0.000000000 0.688800277<br>Al 0.333333333 0.666666667 0.437593675<br>
Al 0.666666667 0.333333333 0.937793675<br>K_POINTS automatic<br> 8 8 8 1 1 1</div>
<div><br><a href="http://band.in">band.in</a></div>
<div>&control<br> title = 2h_aln,<br> prefix = '4h_band',<br> calculation = 'bands' ,<br> restart_mode = 'from_scratch' ,<br>
wf_collect = .false. ,<br> outdir = './' ,<br> wfcdir = './' ,<br> pseudo_dir = './' ,<br> /<br> &SYSTEM<br> ibrav = 4,<br>
celldm(1) = 5.866002785691,<br> celldm(3) = 3.238615289089,<br> nat = 8,<br> ntyp = 2,<br> ecutwfc = 80,</div>
<div> nbnd=46,<br> lspinorb = .true.,<br> noncolin= .true.,<br> starting_magnetization=0.0,</div>
<div> /<br> &ELECTRONS<br> electron_maxstep = 100,<br> conv_thr = 1.D-10,</div>
<div> /<br>ATOMIC_SPECIES<br> N 14.00700 N.rel-pbe-rrkjus.UPF<br> Al 26.98200 Al.rel-pbe-rrkj.UPF<br>ATOMIC_POSITIONS (crystal)<br>N 0.000000000 0.000000000 -0.000722968<br>N 0.000000000 0.000000000 0.499277032<br>
N 0.333333333 0.666666667 0.249293699<br>N 0.666666667 0.333333333 0.749293699<br>Al 0.000000000 0.000000000 0.188800277<br>Al 0.000000000 0.000000000 0.688800277<br>Al 0.333333333 0.666666667 0.437593675<br>
Al 0.666666667 0.333333333 0.937793675<br>K_POINTS<br> 2<br> 0.000000 0.000000 0.000000 1.00<br> 0.000000 0.000000 0.083333 1.00</div>
<div> </div>
<div> </div>
<div><a href="http://bands.in">bands.in</a></div>
<div>&inputpp<br>prefix='4h_band'<br>outdir='./'<br>filband='spin.dat'<br>lsigma(3)=.true.<br>lsym=.true.<br>/<br></div>
<div>Thank you in advance!<br></div>
<div><br>-- <br>Y. C. Cheng<br>Department of Phyics<br>Nanjing University<br>Nanjing 210093<br>P. R. China<br>Tel: 86-25-83592907<br>Email: <a href="mailto:yccheng.nju@gmail.com">yccheng.nju@gmail.com</a><br></div>