Dear Pwscf users,<br>Here I am sending you the input file of Li2S (large band gap semi-conductor) for scf and phonon calculations. I have some queries regarding this<br><br>1. For electronic calculation i am using 8x8x8 k-points which results in only 60 points. Is it enough to do correct electronic calculations?<br>
With these 60 points only, I calculated the bulk mobulus and the equilibrium lattice constants, which matches well with the experiment and other theoritical results.<br><br>2. For phonon calculation, I didnt get the LO-TO splitting. Can you please tell me what more parameters i will use to get the splitting. <br>
I set epsil .true., but it gives the error  <br><br>     from phq_readin : error #         1<br>     no elec. field with metals<br><br>Any suggestion is highly apperciable <br><br><a href="http://li2s.scf.in">li2s.scf.in</a><br>
<br>&CONTROL<br>               calculation = 'scf' ,<br>              restart_mode = 'from_scratch' ,<br>                    outdir = './OUT',<br>                pseudo_dir = '/root/bipul/espresso-4.0.1/pseudo/Li2S',<br>
                   prefix = 'Li2S',<br>             etot_conv_thr = 1.0d-5 ,<br>             forc_conv_thr = 1.0d-4 ,<br>                   tstress = .true. ,<br>                   tprnfor = .true. ,<br>                        dt = 80<br>
 /<br> &SYSTEM<br>                     ibrav = 2,<br>                 celldm(1) =  10.72700,<br>                       nat = 3,<br>                      ntyp = 2 ,<br>                   ecutwfc = 32,<br>                   ecutrho = 600,<br>
                  occupations = 'smearing' ,<br>                    smearing = 'methfessel-paxton',<br>                   degauss = 0.01<br> /<br> &ELECTRONS<br>               mixing_beta = 0.5 ,<br>            conv_thr =  1.0d-8<br>
           diagonalization = 'david' ,<br> /<br> &IONS<br> /<br>ATOMIC_SPECIES<br> S   32.066  S.pw91-van_ak.UPF<br> Li  6.914   Li.pw91-s-van_ak.UPF<br>ATOMIC_POSITIONS (crystal)<br>S  0.0 0.0 0.0<br>Li 0.25 0.25 0.25<br>
Li 0.75 0.75 0.75<br>K_POINTS automatic<br>  8 8 8 1 1 1<br><br><a href="http://li2s.ph.in">li2s.ph.in</a><br><br>phonons of Li2S<br> &inputph<br> ! recover =.true.,<br>  tr2_ph=1.0d-12,<br>  alpha_mix(1)=0.6,<br>  prefix='Li2S',<br>
 ! fildvscf='li2sdv',<br>  amass(1)=32.066,<br>  amass(2)=6.941,<br>  outdir='./OUT',<br>  fildyn='li2s.dyn',<br> ! elph=.true.,<br> ! trans=.true.,<br>  ldisp=.true.<br>  nq1=4, nq2=4, nq3=4<br> /<br>
<br clear="all"><br>-- <br>Premlata Pandit<br>Ph.d. student,<br>Barkatullah university,<br>Bhopal 462026,<br>MP, India <br>