Dear <span style="font-family:arial, sans-serif;font-size:13px;border-collapse:collapse">P S Ghosh：</span><div><span style="font-size:13px"></span><font face="arial, sans-serif"><span style="border-collapse:collapse"><br>
</span></font><div><span style="font-size:13px"></span><font face="arial, sans-serif"><span style="border-collapse:collapse">Do you relax the crystal ?</span></font></div><div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse;">Firstly, relax crystal with "<b>calculation = 'vc-relax' </b>".</span></font></div>

<div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse;">Phonon should be calculated after  vc-relax,</span></font></div><div><br><div class="gmail_quote">


On Wed, May 19, 2010 at 8:11 PM, partha sarathi ghosh <span dir="ltr"><<a href="mailto:parthasarathi13@gmail.com" target="_blank">parthasarathi13@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">


Dear all,<br>             I am trying to do phonon calculation of bcc-Zr from (0,0,0) to (1,1,1) in q-space.But I am getting negative frequencies in several q-points, also my curve is very different from experimental one. I optimized the system w.r.t ecutwf, ecutrho ,conv_thr, k-point sampling .I also tried the same calculation by changing potential also.I am new fellow in this field so I am unable to understand what is happening wrong !!<br>



My input files are :<br>1) <a href="http://zr.scf.in" target="_blank">zr.scf.in</a><br> &control<br>    calculation='scf'<br>    restart_mode='from_scratch',<br>    tstress = .true.<br>    tprnfor = .true.<br>


    prefix='zr',<br>
    pseudo_dir = '/home/general/Desktop/espresso-4.0.5/pseudo/',<br>    outdir='./'<br> /<br> &system<br>    ibrav=  0, celldm(1) =6.7, nat=  1, ntyp= 1,<br>    degauss=0.04,<br>    smearing='mp',<br>



    occupations='smearing',<br>    ecutwfc =35.0<br>    ecutrho = 350.0<br> /<br> &electrons<br>    conv_thr =  1.0d-8<br>    mixing_beta = 0.7<br> /<br>ATOMIC_SPECIES<br> Zr  91.22  Zr.pbe-nsp-van.UPF<br>ATOMIC_POSITIONS<br>



Zr 0.00 0.00 0.00<br>K_POINTS  AUTOMATIC<br> 16 16 16  0 0 0 <br>CELL_PARAMETERS { cubic }<br>  -0.500000000000000   0.500000000000000   0.500000000000000<br>   0.500000000000000  -0.500000000000000   0.500000000000000<br>



   0.500000000000000   0.500000000000000  -0.500000000000000<br> ##########################################<br>2) <a href="http://zr.ph.in" target="_blank">zr.ph.in</a><br>phonons of Zr<br> &inputph<br>  tr2_ph=1.0d-10,<br>


  prefix='zr',<br>
  ldisp=.true.,<br>  nq1=8, nq2=8, nq3=8<br>  amass(1)=91.22,<br>  outdir='./',<br>  fildyn='zr.dyn',<br> /<br>Any one can help me please .  <br>Thanks in advance.<br>P S Ghosh<br>B.A.R.C.<br>India<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>____________________________________<br>Hui Wang<br>School of physics, Nankai University, Tianjin, China<br>
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