<div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:#000000"><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Dear Quantum Espresso users and developers,</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">I
 am trying to use epsilon.x package to get dielectric function for 
metallic alloys. I had no problems with golde-silver. However the same 
was not true to aluminum.</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Having
 Al an FCC lattice, I would expect its optical response to be isotropic.
 I ran VC-RELAX, SCF, NSCF, and Bands calculations, with no major 
difficulties in the pure Al system (ibrav =2, 1 atom at unit cell). The 
results were in agreement with literature and the examples found at QE 
examples folders. Then I moved to epsilon.x and had no success.</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">I've
 tried to increase convergence parameters (conv_thr = 1d-09). As we have
 to use NC pseudopotentials with epsilon.x, I've increased the wave 
function cutoff (Ecutwfc > 200 Ry). Being a metallic system I've 
played around with smearing (tested both gaussian and mv), and degauss. 
Dielectric function showed a minor change with changing degauss.</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">I don't know what else to try! Any suggestions?</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Follows the input files for the vc-relaxed structure:</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">****************<br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;color:rgb(0,0,0)"><font size="2">&CONTROL<br>                       title = 'Au66Al33'<br>                      prefix = 'Au66Al33' ,                 <br>                 calculation = 'nscf',<br>                     disk_io = 'low',<br>                          outdir = './tmp/' ,<br>                  pseudo_dir = './pseudo/'<br>                   verbosity = 'high' ,<br>               etot_conv_thr = 1.0d-8 ,<br>               forc_conv_thr = 1.0d-7 ,<br>                     tstress = .true. ,<br>                     tprnfor = .true. ,<br>/<br>&SYSTEM<br>  ibrav=0,<br>  celldm(1)=12.93669207d0,<br>  nat=12,<br>  ntyp=2,<br>  ecutwfc=200,<br>  ecutrho=600,<br>  input_dft='pbe',<br>  occupations='smearing',<br>  smearing='mv',<br>  degauss=0.02d0,<br>  noinv = .true.,<br>  nosym = .true.,<br>/<br>&ELECTRONS<br>            electron_maxstep = 1000,<br>                    conv_thr = 1d-09 ,<br>                 mixing_mode = 'plain' ,<br>                 mixing_beta = 0.5d0 ,<br>/<br> &IONS       <br> /<br> &CELL<br> /<br>ATOMIC_SPECIES<br>  Al 26.981500d0 Al.UPF<br>  Au 196.967000d0 Au.UPF<br><br>K_POINTS {automatic}<br> 9 9 9 1 1 1  <br><br>CELL_PARAMETERS {alat}<br>   0.988224309   0.000000000   0.000023347<br>   0.000000000   0.477626328   0.000000000<br>   0.000022090   0.000000000   1.334026170<br><br>ATOMIC_POSITIONS {crystal}<br>Al   0.628198968   0.250000000   0.277143747<br>Al     0.128140017   0.250000000   0.222904681<br>Al   0.371801032   0.750000000   0.722856253<br>Al   0.871859983   0.750000000   0.777095319<br>Au   0.147502860   0.250000000   0.920025162<br>Au   0.647627196   0.250000000   0.579877017<br>Au   0.852497140   0.750000000   0.079974838<br>Au   0.352372804   0.750000000   0.420122983<br>Au   0.592675840   0.250000000   0.886918451<br>Au   0.092652971   0.250000000   0.613011168<br>Au   0.407324160   0.750000000   0.113081549<br>Au   0.907347029   0.750000000   0.386988832</font></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">***********</div><div class="gmail_default" style="font-family:tahoma,sans-serif;color:rgb(0,0,0)"><font size="2">&INPUTPP<br>        outdir="./tmp",<br>        prefix="Au66Al33",<br>        calculation="eps",<br>/<br>&ENERGY_GRID<br> smeartype="gauss",<br>        intersmear=0.136d0,<br>        intrasmear=0.0d0,<br>        wmax=10.0d0,<br>        wmin=0.0d0,<br>        nw=500,<br>        shift=0.0d0,<br>/</font></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Thanks in advance</div><font color="#888888"><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Anibal Bezerra</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Federal University of Alfenas</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Alfenas-MG</div><div class="gmail_default" style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Brazil</div></font></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Em sex., 8 de mai. de 2020 às 11:27, Anibal Bezerra <<a href="mailto:anibal.bezerra@unifal-mg.edu.br">anibal.bezerra@unifal-mg.edu.br</a>> escreveu:<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 dir="ltr"><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Dear Quantum Espresso users and developers,</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">I am trying to use epsilon.x package to get dielectric function for metallic alloys. I had no problems with golde-silver. However the same was not true to aluminum.</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Having Al an FCC lattice, I would expect its optical response to be isotropic. I ran VC-RELAX, SCF, NSCF, and Bands calculations, with no major difficulties in the pure Al system (ibrav =2, 1 atom at unit cell). The results were in agreement with literature and the examples found at QE examples folders. Then I moved to epsilon.x and had no success.</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">I've tried to increase convergence parameters (conv_thr = 1d-09). As we have to use NC pseudopotentials with epsilon.x, I've increased the wave function cutoff (Ecutwfc > 200 Ry). Being a metallic system I've played around with smearing (tested both gaussian and mv), and degauss. Dielectric function showed a minor change with changing degauss.</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">I don't know what else to try! Any suggestions?</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Follows the input files for the vc-relaxed structure:</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">****************<br></div><div style="font-family:tahoma,sans-serif;color:rgb(0,0,0)"><font size="2">&CONTROL<br>                       title = 'Au66Al33'<br>                      prefix = 'Au66Al33' ,                 <br>                 calculation = 'nscf',<br>                     disk_io = 'low',<br>                              outdir = './tmp/' ,<br>                  pseudo_dir = './pseudo/'<br>                   verbosity = 'high' ,<br>               etot_conv_thr = 1.0d-8 ,<br>               forc_conv_thr = 1.0d-7 ,<br>                     tstress = .true. ,<br>                     tprnfor = .true. ,<br>/<br>&SYSTEM<br>  ibrav=0,<br>  celldm(1)=12.93669207d0,<br>  nat=12,<br>  ntyp=2,<br>  ecutwfc=200,<br>  ecutrho=600,<br>  input_dft='pbe',<br>  occupations='smearing',<br>  smearing='mv',<br>  degauss=0.02d0,<br>  noinv = .true.,<br>  nosym = .true.,<br>/<br>&ELECTRONS<br>            electron_maxstep = 1000,<br>                    conv_thr = 1d-09 ,<br>                 mixing_mode = 'plain' ,<br>                 mixing_beta = 0.5d0 ,<br>/<br> &IONS       <br> /<br> &CELL<br> /<br>ATOMIC_SPECIES<br>  Al 26.981500d0 Al.UPF<br>  Au 196.967000d0 Au.UPF<br><br>K_POINTS {automatic}<br> 9 9 9 1 1 1  <br><br>CELL_PARAMETERS {alat}<br>   0.988224309   0.000000000   0.000023347<br>   0.000000000   0.477626328   0.000000000<br>   0.000022090   0.000000000   1.334026170<br><br>ATOMIC_POSITIONS {crystal}<br>Al   0.628198968   0.250000000   0.277143747<br>Al     0.128140017   0.250000000   0.222904681<br>Al   0.371801032   0.750000000   0.722856253<br>Al   0.871859983   0.750000000   0.777095319<br>Au   0.147502860   0.250000000   0.920025162<br>Au   0.647627196   0.250000000   0.579877017<br>Au   0.852497140   0.750000000   0.079974838<br>Au   0.352372804   0.750000000   0.420122983<br>Au   0.592675840   0.250000000   0.886918451<br>Au   0.092652971   0.250000000   0.613011168<br>Au   0.407324160   0.750000000   0.113081549<br>Au   0.907347029   0.750000000   0.386988832</font></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">***********</div><div style="font-family:tahoma,sans-serif;color:rgb(0,0,0)"><font size="2">&INPUTPP<br>        outdir="./tmp",<br>        prefix="Au66Al33",<br>        calculation="eps",<br>/<br>&ENERGY_GRID<br> smeartype="gauss",<br>        intersmear=0.136d0,<br>        intrasmear=0.0d0,<br>        wmax=10.0d0,<br>        wmin=0.0d0,<br>        nw=500,<br>        shift=0.0d0,<br>/</font></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Thanks in advance</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)"><br></div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Anibal Bezerra</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Federal University of Alfenas</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Alfenas-MG</div><div style="font-family:tahoma,sans-serif;font-size:large;color:rgb(0,0,0)">Brazil<br> </div></div>
</blockquote></div></div>