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<p>Hello everyone,</p>
<p><br>
</p>
<p>I'm trying to reproduce the dielectric constant of alpha-alumina using PHonon. However, I'm getting values close to third of the actual dielectric constant and cannot figure out why. I also had the same issue with Columbite-(Mg), so it's not a particular
problem with that material system.</p>
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</p>
<p>Here are my SCF and PH input files: </p>
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&control</div>
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calculation='scf',</div>
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outdir='./out',</div>
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prefix='alo',</div>
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pseudo_dir='.',</div>
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tstress=.true.,</div>
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tprnfor=.true.,</div>
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forc_conv_thr=1.0D-8,</div>
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etot_conv_thr=1.0D-6,</div>
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/</div>
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&system</div>
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ibrav=0,</div>
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celldm(1)=9.69051561,</div>
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nat=10,</div>
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ntyp=2,</div>
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ecutwfc=50,</div>
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&electrons</div>
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diago_full_acc=.true.,</div>
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/</div>
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&ions</div>
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ATOMIC_SPECIES</div>
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O 15.9994 O.pbe-mt.UPF</div>
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Al 26.981539 Al.pbe-mt_fhi</div>
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<div>CELL_PARAMETERS alat</div>
<div> 0.444822702 -0.256818507 0.805845773</div>
<div> -0.000000000 0.513637014 0.805845773</div>
<div> -0.444822702 -0.256818507 0.805845773</div>
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<div>ATOMIC_POSITIONS crystal</div>
<div>O 0.058814216 0.749985721 0.441239527</div>
<div>O 0.250014279 0.558760473 0.941185784</div>
<div>O 0.441239527 0.058814216 0.749985721</div>
<div>O 0.558760473 0.941185784 0.250014279</div>
<div>O 0.749985721 0.441239527 0.058814216</div>
<div>O 0.941185784 0.250014279 0.558760473</div>
<div>Al 0.148217545 0.148217545 0.148217545</div>
<div>Al 0.351772827 0.351772827 0.351772827</div>
<div>Al 0.648227173 0.648227173 0.648227173</div>
<div>Al 0.851782455 0.851782455 0.851782455</div>
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<div>K_POINTS automatic</div>
<div>16 16 16 0 0 0</div>
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PH:</div>
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<div>alo_dielectric</div>
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<div>&INPUTPH</div>
<div>tr2_ph=1e-15,</div>
<div>outdir='./out',</div>
<div>prefix='alo',</div>
<div>epsil=.true.,</div>
<div>/</div>
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<div>0 0 0</div>
<div><br>
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<div>Any help would be greatly appreciated.</div>
<div><br>
</div>
<div>Mohamed Elshazly</div>
<div>Edward S. Rogers Department of Electrical and Computer Engineering</div>
<div>University of Toronto</div>
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