Problem for calculation of TiSe2

[sahildani]

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

[hpaudya1]

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

[sahildani]

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.

[hpaudya1]

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

[hlee]

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

[sahildani]

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.

[Vahid]

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