Help with k point selection for EPW

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kikin
Posts: 1
Joined: Thu Feb 08, 2024 9:41 pm
Affiliation: Undergraduate

Help with k point selection for EPW

Post by kikin »

Background:
I am an undergraduate student trying to learn how to use QE and EPW. I lack a lot of fundamental prerequisite knowledge and have been teaching myself a few common concepts to aid in this journey. I have been following the "Superconducting magnesium diboride" tutorial on the EPW website to try and model my own molecule (Indium Tin Oxide (ITO)). I am having trouble finding unit cell or very much crystal structure information on ITO, so I am completely relying on websites like materialsproject.org to help me along.

Issue:
Per the tutorial, I have successfully gotten through scf, phonon, and nscf calculations, however I am having trouble running epw.x and creating an appropriate input file for my structure. Assumably, this is due to my choice of k-points, with my most recent error being "Non-symmetric k-point neighbours!".

Explanation/Information:
In my nscf.in file, I have 208 k-points (generated via https://www.materialscloud.org/work/tools/seekpath from my scf input file) and in my nscf.out file, it also states I have 208 k-points. So, how would I go about assigning nk1, nk2, and nk3 with this value? It doesn't seem to be able to be 3 identical integers like in previous forum discussions (6x6x6 or 8x8x8). There doesn't seem to be obvious information on these 3 values in the materialscloud k-path generator... There very well be more at play here since I am extremely new to these calculations and don't have a firm grasp of the issue. I will paste my input files below. I apologize for my cluelessness and appreciate any help.

scf.in:
&control
calculation='scf',
prefix='ITO',
pseudo_dir = './pseudos/',
outdir='./',
tprnfor = .true.,
tstress = .true.,
etot_conv_thr = 1.0d-05
forc_conv_thr = 1.0d-04
/
&system
degauss = 0.014
ecutwfc = 40
ibrav = 0
nat = 4
ntyp = 3
occupations = 'smearing'
smearing = 'mp'
/
&electrons
conv_thr = 1.7600000000d-09
electron_maxstep = 80
mixing_beta = 0.5
mixing_mode = 'plain'
/
ATOMIC_SPECIES
In 114.818 In.pbe-dn-rrkjus_psl.0.2.2.UPF
O 15.9994 O.pbe-n-kjpaw_psl.0.1.UPF
Sn 118.71 Sn_pbe_v1.uspp.F.UPF
ATOMIC_POSITIONS crystal
O 0.00000000 0.00000000 0.50000000
Sn 0.12500000 0.12500000 0.12500000
In 0.37500000 0.87500000 0.12500000
O 0.71683400 0.00000000 0.50000000
K_POINTS automatic
4 4 4 0 0 0
CELL_PARAMETERS angstrom
10.3857540000 0.0000000000 0.0000000000
0.0000000000 10.3857540000 0.0000000000
0.0000000000 0.0000000000 10.3857540000
-------------------------------------------------------------------
ph.in
--
&inputph
prefix = 'ITO',
fildyn = 'ITO.dyn',
outdir = './',
ldisp = .true.,
trans = .true.,
fildvscf = 'dvscf',
nmix_ph = 15,
alpha_mix(1)=0.1,
nq1=3,
nq2=3,
nq3=3,
tr2_ph=1.0d-14
/
---------------------------------------------------------------------
nscf.in
&control
calculation='bands',
prefix='ITO',
pseudo_dir = './pseudos/',
outdir='./',
tprnfor = .true.,
tstress = .true.,
etot_conv_thr = 1.0d-5
forc_conv_thr = 1.0d-4
/
&system
ibrav = 0,
nat= 4,
ntyp = 3,
ecutwfc = 40
smearing = 'mp'
occupations = 'smearing'
degauss = 0.014
/
&electrons
mixing_mode = 'plain'
mixing_beta = 0.7
conv_thr = 1.0d-9
electron_maxstep = 80
/
ATOMIC_SPECIES
In 114.818 In.pbe-dn-rrkjus_psl.0.2.2.UPF
O 15.9994 O.pbe-n-kjpaw_psl.0.1.UPF
Sn 118.71 Sn_pbe_v1.uspp.F.UPF
ATOMIC_POSITIONS crystal
O 0.00000000 0.00000000 0.50000000
Sn 0.12500000 0.12500000 0.12500000
In 0.37500000 0.87500000 0.12500000
O 0.71683400 0.00000000 0.50000000
K_POINTS crystal
208
0.0000000000 0.0000000000 0.0000000000 1
0.0454545455 0.0000000000 0.0000000000 1
0.0909090909 0.0000000000 0.0000000000 1
0.1363636364 0.0000000000 0.0000000000 1
0.1818181818 0.0000000000 0.0000000000 1
0.2272727273 0.0000000000 0.0000000000 1
0.2727272727 0.0000000000 0.0000000000 1
0.3181818182 0.0000000000 0.0000000000 1
0.3636363636 0.0000000000 0.0000000000 1
0.4090909091 0.0000000000 0.0000000000 1
0.4545454545 0.0000000000 0.0000000000 1
0.5000000000 0.0000000000 0.0000000000 1
0.0000000000 0.5000000000 0.0000000000 1
0.0000000000 0.4545454545 0.0000000000 1
0.0000000000 0.4090909091 0.0000000000 1
0.0000000000 0.3636363636 0.0000000000 1
0.0000000000 0.3181818182 0.0000000000 1
0.0000000000 0.2727272727 0.0000000000 1
0.0000000000 0.2272727273 0.0000000000 1
0.0000000000 0.1818181818 0.0000000000 1
0.0000000000 0.1363636364 0.0000000000 1
0.0000000000 0.0909090909 0.0000000000 1
0.0000000000 0.0454545455 0.0000000000 1
0.0000000000 0.0000000000 0.0000000000 1
0.0000000000 0.0000000000 0.0454545455 1
0.0000000000 0.0000000000 0.0909090909 1
0.0000000000 0.0000000000 0.1363636364 1
0.0000000000 0.0000000000 0.1818181818 1
0.0000000000 0.0000000000 0.2272727273 1
0.0000000000 0.0000000000 0.2727272727 1
0.0000000000 0.0000000000 0.3181818182 1
0.0000000000 0.0000000000 0.3636363636 1
0.0000000000 0.0000000000 0.4090909091 1
0.0000000000 0.0000000000 0.4545454545 1
0.0000000000 0.0000000000 0.5000000000 1
0.5000000000 0.5000000000 0.5000000000 1
0.4736842105 0.4736842105 0.4736842105 1
0.4473684211 0.4473684211 0.4473684211 1
0.4210526316 0.4210526316 0.4210526316 1
0.3947368421 0.3947368421 0.3947368421 1
0.3684210526 0.3684210526 0.3684210526 1
0.3421052632 0.3421052632 0.3421052632 1
0.3157894737 0.3157894737 0.3157894737 1
0.2894736842 0.2894736842 0.2894736842 1
0.2631578947 0.2631578947 0.2631578947 1
0.2368421053 0.2368421053 0.2368421053 1
0.2105263158 0.2105263158 0.2105263158 1
0.1842105263 0.1842105263 0.1842105263 1
0.1578947368 0.1578947368 0.1578947368 1
0.1315789474 0.1315789474 0.1315789474 1
0.1052631579 0.1052631579 0.1052631579 1
0.0789473684 0.0789473684 0.0789473684 1
0.0526315789 0.0526315789 0.0526315789 1
0.0263157895 0.0263157895 0.0263157895 1
0.0000000000 0.0000000000 0.0000000000 1
0.0000000000 0.0312500000 0.0312500000 1
0.0000000000 0.0625000000 0.0625000000 1
0.0000000000 0.0937500000 0.0937500000 1
0.0000000000 0.1250000000 0.1250000000 1
0.0000000000 0.1562500000 0.1562500000 1
0.0000000000 0.1875000000 0.1875000000 1
0.0000000000 0.2187500000 0.2187500000 1
0.0000000000 0.2500000000 0.2500000000 1
0.0000000000 0.2812500000 0.2812500000 1
0.0000000000 0.3125000000 0.3125000000 1
0.0000000000 0.3437500000 0.3437500000 1
0.0000000000 0.3750000000 0.3750000000 1
0.0000000000 0.4062500000 0.4062500000 1
0.0000000000 0.4375000000 0.4375000000 1
0.0000000000 0.4687500000 0.4687500000 1
0.0000000000 0.5000000000 0.5000000000 1
0.5000000000 0.0000000000 0.5000000000 1
0.4687500000 0.0000000000 0.4687500000 1
0.4375000000 0.0000000000 0.4375000000 1
0.4062500000 0.0000000000 0.4062500000 1
0.3750000000 0.0000000000 0.3750000000 1
0.3437500000 0.0000000000 0.3437500000 1
0.3125000000 0.0000000000 0.3125000000 1
0.2812500000 0.0000000000 0.2812500000 1
0.2500000000 0.0000000000 0.2500000000 1
0.2187500000 0.0000000000 0.2187500000 1
0.1875000000 0.0000000000 0.1875000000 1
0.1562500000 0.0000000000 0.1562500000 1
0.1250000000 0.0000000000 0.1250000000 1
0.0937500000 0.0000000000 0.0937500000 1
0.0625000000 0.0000000000 0.0625000000 1
0.0312500000 0.0000000000 0.0312500000 1
0.0000000000 0.0000000000 0.0000000000 1
0.0312500000 0.0312500000 0.0000000000 1
0.0625000000 0.0625000000 0.0000000000 1
0.0937500000 0.0937500000 0.0000000000 1
0.1250000000 0.1250000000 0.0000000000 1
0.1562500000 0.1562500000 0.0000000000 1
0.1875000000 0.1875000000 0.0000000000 1
0.2187500000 0.2187500000 0.0000000000 1
0.2500000000 0.2500000000 0.0000000000 1
0.2812500000 0.2812500000 0.0000000000 1
0.3125000000 0.3125000000 0.0000000000 1
0.3437500000 0.3437500000 0.0000000000 1
0.3750000000 0.3750000000 0.0000000000 1
0.4062500000 0.4062500000 0.0000000000 1
0.4375000000 0.4375000000 0.0000000000 1
0.4687500000 0.4687500000 0.0000000000 1
0.5000000000 0.5000000000 0.0000000000 1
0.0000000000 0.0000000000 0.0000000000 1
-0.0454545455 0.0000000000 0.0000000000 1
-0.0909090909 0.0000000000 0.0000000000 1
-0.1363636364 0.0000000000 0.0000000000 1
-0.1818181818 0.0000000000 0.0000000000 1
-0.2272727273 0.0000000000 0.0000000000 1
-0.2727272727 0.0000000000 0.0000000000 1
-0.3181818182 0.0000000000 0.0000000000 1
-0.3636363636 0.0000000000 0.0000000000 1
-0.4090909091 0.0000000000 0.0000000000 1
-0.4545454545 0.0000000000 0.0000000000 1
-0.5000000000 0.0000000000 0.0000000000 1
0.0000000000 -0.5000000000 0.0000000000 1
0.0000000000 -0.4545454545 0.0000000000 1
0.0000000000 -0.4090909091 0.0000000000 1
0.0000000000 -0.3636363636 0.0000000000 1
0.0000000000 -0.3181818182 0.0000000000 1
0.0000000000 -0.2727272727 0.0000000000 1
0.0000000000 -0.2272727273 0.0000000000 1
0.0000000000 -0.1818181818 0.0000000000 1
0.0000000000 -0.1363636364 0.0000000000 1
0.0000000000 -0.0909090909 0.0000000000 1
0.0000000000 -0.0454545455 0.0000000000 1
0.0000000000 0.0000000000 0.0000000000 1
0.0000000000 0.0000000000 -0.0454545455 1
0.0000000000 0.0000000000 -0.0909090909 1
0.0000000000 0.0000000000 -0.1363636364 1
0.0000000000 0.0000000000 -0.1818181818 1
0.0000000000 0.0000000000 -0.2272727273 1
0.0000000000 0.0000000000 -0.2727272727 1
0.0000000000 0.0000000000 -0.3181818182 1
0.0000000000 0.0000000000 -0.3636363636 1
0.0000000000 0.0000000000 -0.4090909091 1
0.0000000000 0.0000000000 -0.4545454545 1
0.0000000000 0.0000000000 -0.5000000000 1
-0.5000000000 -0.5000000000 -0.5000000000 1
-0.4736842105 -0.4736842105 -0.4736842105 1
-0.4473684211 -0.4473684211 -0.4473684211 1
-0.4210526316 -0.4210526316 -0.4210526316 1
-0.3947368421 -0.3947368421 -0.3947368421 1
-0.3684210526 -0.3684210526 -0.3684210526 1
-0.3421052632 -0.3421052632 -0.3421052632 1
-0.3157894737 -0.3157894737 -0.3157894737 1
-0.2894736842 -0.2894736842 -0.2894736842 1
-0.2631578947 -0.2631578947 -0.2631578947 1
-0.2368421053 -0.2368421053 -0.2368421053 1
-0.2105263158 -0.2105263158 -0.2105263158 1
-0.1842105263 -0.1842105263 -0.1842105263 1
-0.1578947368 -0.1578947368 -0.1578947368 1
-0.1315789474 -0.1315789474 -0.1315789474 1
-0.1052631579 -0.1052631579 -0.1052631579 1
-0.0789473684 -0.0789473684 -0.0789473684 1
-0.0526315789 -0.0526315789 -0.0526315789 1
-0.0263157895 -0.0263157895 -0.0263157895 1
0.0000000000 0.0000000000 0.0000000000 1
0.0000000000 -0.0312500000 -0.0312500000 1
0.0000000000 -0.0625000000 -0.0625000000 1
0.0000000000 -0.0937500000 -0.0937500000 1
0.0000000000 -0.1250000000 -0.1250000000 1
0.0000000000 -0.1562500000 -0.1562500000 1
0.0000000000 -0.1875000000 -0.1875000000 1
0.0000000000 -0.2187500000 -0.2187500000 1
0.0000000000 -0.2500000000 -0.2500000000 1
0.0000000000 -0.2812500000 -0.2812500000 1
0.0000000000 -0.3125000000 -0.3125000000 1
0.0000000000 -0.3437500000 -0.3437500000 1
0.0000000000 -0.3750000000 -0.3750000000 1
0.0000000000 -0.4062500000 -0.4062500000 1
0.0000000000 -0.4375000000 -0.4375000000 1
0.0000000000 -0.4687500000 -0.4687500000 1
0.0000000000 -0.5000000000 -0.5000000000 1
-0.5000000000 0.0000000000 -0.5000000000 1
-0.4687500000 0.0000000000 -0.4687500000 1
-0.4375000000 0.0000000000 -0.4375000000 1
-0.4062500000 0.0000000000 -0.4062500000 1
-0.3750000000 0.0000000000 -0.3750000000 1
-0.3437500000 0.0000000000 -0.3437500000 1
-0.3125000000 0.0000000000 -0.3125000000 1
-0.2812500000 0.0000000000 -0.2812500000 1
-0.2500000000 0.0000000000 -0.2500000000 1
-0.2187500000 0.0000000000 -0.2187500000 1
-0.1875000000 0.0000000000 -0.1875000000 1
-0.1562500000 0.0000000000 -0.1562500000 1
-0.1250000000 0.0000000000 -0.1250000000 1
-0.0937500000 0.0000000000 -0.0937500000 1
-0.0625000000 0.0000000000 -0.0625000000 1
-0.0312500000 0.0000000000 -0.0312500000 1
0.0000000000 0.0000000000 0.0000000000 1
-0.0312500000 -0.0312500000 0.0000000000 1
-0.0625000000 -0.0625000000 0.0000000000 1
-0.0937500000 -0.0937500000 0.0000000000 1
-0.1250000000 -0.1250000000 0.0000000000 1
-0.1562500000 -0.1562500000 0.0000000000 1
-0.1875000000 -0.1875000000 0.0000000000 1
-0.2187500000 -0.2187500000 0.0000000000 1
-0.2500000000 -0.2500000000 0.0000000000 1
-0.2812500000 -0.2812500000 0.0000000000 1
-0.3125000000 -0.3125000000 0.0000000000 1
-0.3437500000 -0.3437500000 0.0000000000 1
-0.3750000000 -0.3750000000 0.0000000000 1
-0.4062500000 -0.4062500000 0.0000000000 1
-0.4375000000 -0.4375000000 0.0000000000 1
-0.4687500000 -0.4687500000 0.0000000000 1
-0.5000000000 -0.5000000000 0.0000000000 1
CELL_PARAMETERS angstrom
10.3857540000 0.0000000000 0.0000000000
0.0000000000 10.3857540000 0.0000000000
0.0000000000 0.0000000000 10.3857540000
---------------------------------------------------------------------
epw.in
--
&inputepw
prefix = 'ITO',
outdir = './'

ep_coupling = .true.
elph = .true.
epbwrite = .true.
epbread = .false.

epwwrite = .true.
epwread = .false.

etf_mem = 1

nbndsub = 20,

wannierize = .true.
num_iter = 500
dis_froz_max= 8.8
proj(1) = 'random'

iverbosity = 2

eps_acustic = 2.0
ephwrite = .true.

fsthick = 0.4 ! eV
degaussw = 0.10 ! eV
nsmear = 1
delta_smear = 0.04 ! eV

degaussq = 0.5 ! meV
nqstep = 500

eliashberg = .true.

laniso = .true.
limag = .true.
lpade = .true.

conv_thr_iaxis = 1.0d-4

wscut = 1.0

nstemp = 1
temps = 15.00

nsiter = 500

muc = 0.16

dvscf_dir = './save'

nk1 = 13
nk2 = 16
nk3 = 1

nq1 = 3
nq2 = 3
nq3 = 3

mp_mesh_k = .true.
nkf1 = 20
nkf2 = 20
nkf3 = 20

nqf1 = 20
nqf2 = 20
nqf3 = 20
/
---------------------------------------------------

Thank you,
Henry Garland

hmori
Posts: 13
Joined: Fri Mar 17, 2023 4:28 pm
Affiliation: Binghamton University

Re: Help with k point selection for EPW

Post by hmori »

Hello Henry,

In the nscf calculation just before running epw, you should use a homogeneous grid of nk1 x nk2 x nk3. Note that you cannot automatically specify the k points as in the scf calculation, which means you do not use "K_POINTS automatic". We strongly suggest using "kmesh.pl", that is the script to create a k-point list for Wannier90 and EPW. This script is located in the Wannier90 directory: /path-to-qe/wannier90-X.X.X/utility/kmesh.pl

If you take nk1 x nk2 x nk3 = 6x6x6, you can run the script to generate a klist as:
./kmesh.pl 6 6 6
and then overwrite the list of your nscf.in with the output klist.
nk1 x nk2 x nk3 should be commensurate with nq1 x nq2 x nq3. For example, if you take 4x4x4 in the phonon calculation, you can take 4x4x4, 8x8x8, 12x12x12, ... in an nscf calculation.
The k-list in your nscf.in generated by SeeK-path is one for plotting bands, not the list of a homogeneous grid. I guess the list corresponds to "Suggested path" displayed in "Reciprocal space and Brillouin-zone information".

Best regards,
Hitoshi

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