<div dir="ltr">Thank you all for your response. For computing the Z* and epilson for polar materials, I saw in a couple of tutorials that I have to first compute the dynamic matrix using dynmat.x at the Gamma point setting  epsil=.true.. For the remaining q-points, I have to add the non-analytical part in the input of the dynmat.x. Is this the correct for version 6.4.1 or should I just have to set some flags? <div><br></div><div> Also, is there a difference if I use matdyn.x instead of dynmat.x? </div><div><br></div><div>Regards,</div><div>Sheikh</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Dec 30, 2019 at 5:34 PM Stefano de Gironcoli <<a href="mailto:degironc@sissa.it">degironc@sissa.it</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
  
    
  
  <div bgcolor="#FFFFFF">
    <p><tt>the order of the entries in the pseudopotential list or in
        the atomic position list should not affect the result.</tt></p>
    <p><tt>however you are not changing only the order. <br>
      </tt></p>
    <p><tt>1) you are also swapping the two atoms... this too should not
        change anything but is not the same as changing the order only
        :)<br>
      </tt></p>
    <p><tt>2) the first calculation is metallic (with a quite large
        gaussian smearing, 0.05 Ry is ~ 0.7 eV) the second uses the
        default insulating setting. THIS may have a big impact, for two
        reasons: i) the fundamental gap in AlSb, if I remember
        correctly, is not very large .. comparable to the smearing width
        used; ii) being AlSb a polar material the vibrational properties
        have a non analytic component ruled by the macroscopic
        dielectric properties (Z*, epsilon_infty) that are disabled in
        the phonon calculation of metals (where epsilon_infty diverges).
        <br>
      </tt></p>
    <p><tt>Additionally, in the phonon calculation step you should make
        sure you do compute Z* and epsilon and include them in the
        subsequent phonon dispersion calculation step.  <br>
      </tt></p>
    <p><tt>HTH</tt></p>
    <p><tt>stefano</tt><br>
    </p>
    <div>On 30/12/19 23:07, Sheikh Ziauddin
      Ahmed wrote:<br>
    </div>
    <blockquote type="cite">
      
      <div dir="ltr">I am trying to calculate the phonon dispersion of
        AlSb. I am getting two different results depending on how I am
        introducing the atoms in the SCF calculation. Will the order of
        the atom change the symmetry of the zinc blende AlSb?
        <div><br>
        </div>
        <div>In the first case the input deck is: </div>
        <div>&system<br>
              ibrav=2, nat=2, ntyp=2,<br>
              ecutwfc = 50, ecutrho = 500,<br>
              occupations='smearing',<br>
              smearing='gauss',<br>
              degauss=0.05,<br>
              celldm(1)=11.5944146,<br>
           /<br>
           &electrons<br>
              conv_thr    = 1.0e-12<br>
              mixing_beta = 0.7<br>
              mixing_mode = 'local-TF'<br>
           /<br>
          ATOMIC_SPECIES<br>
           Al 26.98 al_lda_v1.uspp.F.UPF<br>
           Sb 121.76 sb_lda_v1.4.uspp.F.UPF<br>
          ATOMIC_POSITIONS (alat)<br>
           Al 0.0   0.0   0.0<br>
           Sb 0.25  0.25  0.25<br>
          K_POINTS automatic<br>
          6 6 6 0 0 0<br>
        </div>
        <div><br clear="all">
          <div>In the second case the input deck is: </div>
          <div> &system<br>
                ibrav=2, nat=2, ntyp=2,<br>
                ecutwfc = 50, ecutrho = 500,<br>
                !occupations='smearing',<br>
                !smearing='gauss',<br>
                !degauss=0.05,<br>
                celldm(1)=11.5944146,<br>
             /<br>
             &electrons<br>
                conv_thr    = 1.0e-12<br>
                mixing_beta = 0.7<br>
                mixing_mode = 'local-TF'<br>
             /<br>
            ATOMIC_SPECIES<br>
             Sb 121.76 sb_lda_v1.4.uspp.F.UPF<br>
             Al 26.98 al_lda_v1.uspp.F.UPF<br>
            ATOMIC_POSITIONS (alat)<br>
             Sb 0.0   0.0   0.0<br>
             Al 0.25  0.25  0.25<br>
            K_POINTS automatic<br>
            6 6 6 0 0 0<br>
          </div>
          <div><br>
          </div>
          <div>Thanks in advance!</div>
          -- <br>
          <div dir="ltr">
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                                <div style="font-size:12.8px"><font color="#444444"><b>Sheikh Ziauddin
                                      Ahmed </b></font></div>
                                <div style="font-size:12.8px"><font color="#444444">PhD Candidate</font></div>
                                <div style="font-size:12.8px"><font color="#444444">Charles L. Brown
                                    Department of Electrical and
                                    Computer Engineering</font></div>
                                <div style="font-size:12.8px"><font color="#444444">University of
                                    Virginia</font></div>
                                <div style="font-size:12.8px"><font color="#444444">Email<font color="#888888">:</font><a href="mailto:sza9wz@virginia.edu" target="_blank">sza9wz<u>@virginia.edu</u></a></font></div>
                                <div>
                                  <div style="font-size:12.8px"><font color="#444444">LinkedIn</font><font color="#000000">: </font><span style="color:rgb(136,136,136);font-size:12.8px"><a href="https://www.linkedin.com/in/sheikh-ziauddin-ahmed" target="_blank">https://www.linkedin.com/in/sheikh-ziauddin-ahmed</a></span></div>
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                    </span></div>
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Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso" rel="noreferrer" target="_blank">www.max-centre.eu/quantum-espresso</a>)<br>
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<a href="https://lists.quantum-espresso.org/mailman/listinfo/users" rel="noreferrer" target="_blank">https://lists.quantum-espresso.org/mailman/listinfo/users</a></blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div style="margin-bottom:0px;margin-left:0px;padding-bottom:5px"><div><div dir="ltr"><span><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div style="font-size:12.8px"><font color="#444444"><b>Sheikh Ziauddin Ahmed </b></font></div><div style="font-size:12.8px"><font color="#444444">PhD Candidate</font></div><div style="font-size:12.8px"><font color="#444444">Charles L. Brown Department of Electrical and Computer Engineering</font></div><div style="font-size:12.8px"><font color="#444444">University of Virginia</font></div><div style="font-size:12.8px"><font color="#444444">Email<font color="#888888">:</font><a href="mailto:sza9wz@virginia.edu" target="_blank">sza9wz<u>@virginia.edu</u></a></font></div><div><div style="font-size:12.8px"><font color="#444444">LinkedIn</font><font color="#000000">: </font><span style="color:rgb(136,136,136);font-size:12.8px"><a href="https://www.linkedin.com/in/sheikh-ziauddin-ahmed" target="_blank">https://www.linkedin.com/in/sheikh-ziauddin-ahmed</a></span></div></div></div></div></div></div></div></span></div><div style="font-size:12.8px"></div></div></div><div style="font-size:12.8px"></div></div></div>