EPW Forum

Dear all,

I am facing problem for calculation of Resistivity of 2d TiSe2 material.
Here I am attaching the scf.in and also the epw.in file for reference.

&CONTROL
calculation = 'scf'
etot_conv_thr = 1.0000000000d-06
forc_conv_thr = 1.0000000000d-05
outdir = './'
prefix = 'TiSe2'
pseudo_dir = '../pp/'
tprnfor = .true.
tstress = .true.
verbosity = 'high'
forc_conv_thr = 0.001
/
&SYSTEM
degauss = 0.008
ecutwfc = 85
ecutrho = 500
ibrav = 0
nat = 3
nosym = .false.
ntyp = 2
occupations = 'smearing'
smearing = 'm-p'
/
&ELECTRONS
conv_thr = 1.0000000000d-10
electron_maxstep = 200
mixing_beta = 7.0000000000d-01
startingpot = 'atomic'
startingwfc = 'atomic+random'
/
ATOMIC_SPECIES
Se 78.96 Se.pbe-dn-kjpaw_psl.1.0.0.UPF
Ti 47.867 Ti.pbe-spn-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS crystal
Ti -0.0000000000 0.0000000000 0.7499999830
Se 0.6666669680 0.3333329860 0.8896337268
Se 0.3333329900 0.6666669950 0.6103663082

K_POINTS automatic
15 15 1 0 0 0
CELL_PARAMETERS angstrom
3.533510971 -0.000000000 0.000000000
-1.766755485 3.060110265 0.000000000
-0.000000000 -0.000000000 11.135980227

epw.in

&inputepw
prefix = 'TiSe2',
amass(1) = 78.96,
amass(2) = 47.867,
outdir = './'

elph = .true.
kmaps = .false.
epbwrite = .true.
epbread = .false.

epwwrite = .true.
epwread = .false.

nbndsub = 10,
bands_skipped = 'exclude_bands = 1-5'

wannierize = .true.
num_iter = 300
dis_win_max = 21
dis_win_min = -3
dis_froz_min= -3
dis_froz_max= 13.5
proj(1) = 'random'

wdata(1) = 'bands_plot = .true.'
wdata(2) = 'Begin Kpoint_Path'
wdata(3) = 'G 0.00 0.00 0.00 M 0.00 0.50 0.00'
wdata(4) = 'M 0.00 0.50 0.00 K 0.333 0.333 0'
wdata(5) = 'K 0.333 0.333 0.0 G 0.00 0.00 0.00'
wdata(6) = 'End Kpoint_Path'
wdata(7) = 'bands_plot_format = gnuplot'


iverbosity = 0

elecselfen = .false.
phonselfen = .true.

fsthick = 6 ! eV
temps = 0.075 ! K
degaussw = 0.05 ! eV

a2f = .true.

dvscf_dir = '../Phonon/save'
system_2d = .true.
nk1 = 16
nk2 = 16
nk3 = 1

nq1 = 5
nq2 = 5
nq3 = 1

nkf1 = 32
nkf2 = 32
nkf3 = 1

nqf1 = 16
nqf2 = 16
nqf3 = 1
/


and shows error as listed below

task # 0
from elphon_shuffle_wrap : error # 1
Problem with modes file

Hi sahildani,

It looks like the code could not read 'patterns' files. Please make sure it is saved correctly in 'prefix.phsave' inside dvscf_dir = '../Phonon/save'

Best,
Hari

Hi
Thanks for reply. I am checked the save directory as you said. I think all the files are in save directory also patterns files are also there.

Hi sahildani,

Can you also make sure patterns.xx.yy are present in TiSe2.phsave? Also, is the "dvscf_dir = '../Phonon/save' " path correct for the save directory?

I think it should work.

Best,
Hari

Dear sahildani:

nk1 = 16
nk2 = 16
nk3 = 1

nq1 = 5
nq2 = 5
nq3 = 1

In addition to Hari's anwer, I would like to point out that your k coarse grids are incommensurate with q coarse grids.

system_2d = .true.

Although it is not directly related to your current issue, the current version of EPW doesn't support the 2D case.

Lastly, I would like to ask you to study and understand the basic examples in the EPW/examples before the production run for your research.

Sincerley,

H. Lee

Dear hlee Sir,

Thanks for your reply.

I will check. But I am little confused about how to calculate the superconductivity in 2d materials.
People have done that earlier for example CoO2 also for KGe2.

How they do that.

Dear EPW users,

On this thread, it is stated that

"the current version of EPW doesn't support the 2D case". I am assuming that this is for polar materials. What about non-polar 2D materials such as graphene. Does EPW support non-polar 2D materials? Or should they be still treated as 3D with a few k/q points along the vacuum?

I am asking this because I tried graphene with EPW-5.3 but the scattering rates are quite large (~5000/ps at 0.3eV from Fermi level) and is inconsistent with Fig. 1 of Professor Giustino's paper of PRL99, 086804, 2007.

Thank you,
Vahid

Vahid Askarpour
Department of physics and atmospheric science
Dalhousie University
Halifax, NS
CANADA