<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>