[QE-users] Epsilon.x code returns anisotropic dieletric function for FCC Aluminium
Anibal Bezerra
anibal.bezerra at unifal-mg.edu.br
Fri May 8 16:30:29 CEST 2020
Dear Quantum Espresso users and developers,
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.
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.
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.
I don't know what else to try! Any suggestions?
Follows the input files for the vc-relaxed structure:
****************
&CONTROL
title = 'Au66Al33'
prefix = 'Au66Al33' ,
calculation = 'nscf',
disk_io = 'low',
outdir = './tmp/' ,
pseudo_dir = './pseudo/'
verbosity = 'high' ,
etot_conv_thr = 1.0d-8 ,
forc_conv_thr = 1.0d-7 ,
tstress = .true. ,
tprnfor = .true. ,
/
&SYSTEM
ibrav=0,
celldm(1)=12.93669207d0,
nat=12,
ntyp=2,
ecutwfc=200,
ecutrho=600,
input_dft='pbe',
occupations='smearing',
smearing='mv',
degauss=0.02d0,
noinv = .true.,
nosym = .true.,
/
&ELECTRONS
electron_maxstep = 1000,
conv_thr = 1d-09 ,
mixing_mode = 'plain' ,
mixing_beta = 0.5d0 ,
/
&IONS
/
&CELL
/
ATOMIC_SPECIES
Al 26.981500d0 Al.UPF
Au 196.967000d0 Au.UPF
K_POINTS {automatic}
9 9 9 1 1 1
CELL_PARAMETERS {alat}
0.988224309 0.000000000 0.000023347
0.000000000 0.477626328 0.000000000
0.000022090 0.000000000 1.334026170
ATOMIC_POSITIONS {crystal}
Al 0.628198968 0.250000000 0.277143747
Al 0.128140017 0.250000000 0.222904681
Al 0.371801032 0.750000000 0.722856253
Al 0.871859983 0.750000000 0.777095319
Au 0.147502860 0.250000000 0.920025162
Au 0.647627196 0.250000000 0.579877017
Au 0.852497140 0.750000000 0.079974838
Au 0.352372804 0.750000000 0.420122983
Au 0.592675840 0.250000000 0.886918451
Au 0.092652971 0.250000000 0.613011168
Au 0.407324160 0.750000000 0.113081549
Au 0.907347029 0.750000000 0.386988832
***********
&INPUTPP
outdir="./tmp",
prefix="Au66Al33",
calculation="eps",
/
&ENERGY_GRID
smeartype="gauss",
intersmear=0.136d0,
intrasmear=0.0d0,
wmax=10.0d0,
wmin=0.0d0,
nw=500,
shift=0.0d0,
/
Thanks in advance
Anibal Bezerra
Federal University of Alfenas
Alfenas-MG
Brazil
Em sex., 8 de mai. de 2020 às 11:27, Anibal Bezerra <
anibal.bezerra at unifal-mg.edu.br> escreveu:
> Dear Quantum Espresso users and developers,
>
> 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.
>
> 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.
>
> 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.
>
> I don't know what else to try! Any suggestions?
>
> Follows the input files for the vc-relaxed structure:
> ****************
> &CONTROL
> title = 'Au66Al33'
> prefix = 'Au66Al33' ,
> calculation = 'nscf',
> disk_io = 'low',
> outdir = './tmp/' ,
> pseudo_dir = './pseudo/'
> verbosity = 'high' ,
> etot_conv_thr = 1.0d-8 ,
> forc_conv_thr = 1.0d-7 ,
> tstress = .true. ,
> tprnfor = .true. ,
> /
> &SYSTEM
> ibrav=0,
> celldm(1)=12.93669207d0,
> nat=12,
> ntyp=2,
> ecutwfc=200,
> ecutrho=600,
> input_dft='pbe',
> occupations='smearing',
> smearing='mv',
> degauss=0.02d0,
> noinv = .true.,
> nosym = .true.,
> /
> &ELECTRONS
> electron_maxstep = 1000,
> conv_thr = 1d-09 ,
> mixing_mode = 'plain' ,
> mixing_beta = 0.5d0 ,
> /
> &IONS
> /
> &CELL
> /
> ATOMIC_SPECIES
> Al 26.981500d0 Al.UPF
> Au 196.967000d0 Au.UPF
>
> K_POINTS {automatic}
> 9 9 9 1 1 1
>
> CELL_PARAMETERS {alat}
> 0.988224309 0.000000000 0.000023347
> 0.000000000 0.477626328 0.000000000
> 0.000022090 0.000000000 1.334026170
>
> ATOMIC_POSITIONS {crystal}
> Al 0.628198968 0.250000000 0.277143747
> Al 0.128140017 0.250000000 0.222904681
> Al 0.371801032 0.750000000 0.722856253
> Al 0.871859983 0.750000000 0.777095319
> Au 0.147502860 0.250000000 0.920025162
> Au 0.647627196 0.250000000 0.579877017
> Au 0.852497140 0.750000000 0.079974838
> Au 0.352372804 0.750000000 0.420122983
> Au 0.592675840 0.250000000 0.886918451
> Au 0.092652971 0.250000000 0.613011168
> Au 0.407324160 0.750000000 0.113081549
> Au 0.907347029 0.750000000 0.386988832
> ***********
> &INPUTPP
> outdir="./tmp",
> prefix="Au66Al33",
> calculation="eps",
> /
> &ENERGY_GRID
> smeartype="gauss",
> intersmear=0.136d0,
> intrasmear=0.0d0,
> wmax=10.0d0,
> wmin=0.0d0,
> nw=500,
> shift=0.0d0,
> /
>
> Thanks in advance
>
> Anibal Bezerra
> Federal University of Alfenas
> Alfenas-MG
> Brazil
>
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