Regarding Memory problem and different Tc values

[appalakondaiah]

Dear all,

I am facing memory problem (memory per pool : ~= -15.9994 Gb) and nsiw(1 ) = ****** as well as stopped for my compound with low nkf1,nkf2,nqf1,nqf2 as 8X8 mesh (by following MgB2 tutorial). The calculation for the same compound is successful by following the Pb example with nkf1,nkf2,nqf1,nqf2 as 64X64 mesh.

Furthermore, I observed that the obtained Tc and lambda values are different by followed from MgB2 and Pb tutorials, which is puzzled me !!!.

Here with I am attaching my inputs and outputs for the reference. Kindly suggest me the path for this issue

My outputs
epw.out as followed from MgB2 tutorial

lambda_max = 33.1017563 lambda_k_max = 1.9987828

Electron-phonon coupling strength = 0.7762450

Estimated Allen-Dynes Tc = 4.0881084 K for muc = 0.16000

Estimated BCS superconducting gap = 0.0006200 eV

temp( 1) = 0.0000 K

Solve anisotropic Eliashberg equations on imaginary-axis

Total number of frequency points nsiw ( 1 ) = ******
Cutoff frequency wscut = 0.0000


Size of allocated memory per pool : ~= -15.9994 Gb

epw.out as followed from Pb tutorial

===================================================================
Eliashberg Spectral Function in the Migdal Approximation
===================================================================

lambda : 1.6675437
lambda_tr : 2.8587677

Estimated Allen-Dynes Tc

logavg = 0.0005598 l_a2F = 1.6642737
mu = 0.10 Tc = 11.054908749205 K
mu = 0.12 Tc = 10.471116908649 K
mu = 0.14 Tc = 9.886509646407 K
mu = 0.16 Tc = 9.302052307390 K
mu = 0.18 Tc = 8.718829782781 K
mu = 0.20 Tc = 8.138057082013 K
a2F : 5.39s CPU 5.48s WALL ( 1 calls)

My inputs
As followed By MgB2 tutorial
--

&inputepw
prefix = 'NbSe2',
amass(1) = 92.91,
amass(2) = 78.96,
outdir = './'

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

epwwrite = .true.
epwread = .false.

etf_mem = .true.

nbndsub = 5,
nbndskip = 0

nbndsub = 13
efermi_read = .true.
fermi_energy= -2.3622
wannierize = .true.
num_iter = 500
dis_win_min = -3.0
dis_froz_min = -2.2
dis_froz_max = 1.0
dis_win_max = 5.0

proj(1) = 'Nb:d'
proj(2) = 'Se:l=0;l=1'
wdata(1) = 'bands_plot = .true.'
wdata(2) = 'begin kpoint_path'
wdata(3) = 'G 0.00 0.00 0.00 M 0.50 0.00 0.00'
wdata(4) = 'M 0.50 0.00 0.00 K 0.33 0.33 0.00'
wdata(5) = 'K 0.33 0.33 0.00 G 0.00 0.00 0.00'
wdata(6) = 'end kpoint_path'
wdata(7) = 'bands_plot_format = xmgr'
wdata(8) = 'guiding_centres = TRUE '


iverbosity = 2

elinterp = .true.
phinterp = .true.

tshuffle2 = .true.
tphases = .false.

parallel_k = .true.
parallel_q = .false.

eps_acustic = 2.0 ! Lowest boundary for the
ephwrite = .true. ! Writes .ephmat files used when wliasberg = .true.

fsthick = 2.0 ! eV
eptemp = 0 ! K
degaussw = 0.50 ! 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 = 4.0 ! eV Upper limit over frequency integration/summation in the Elisashberg eq

nstemp = 1
tempsmin = 0.00
tempsmax = 4.00

nsiter = 500

muc = 0.16
dvscf_dir = '../phonons/save'


nkf1 = 8
nkf2 = 8
nkf3 = 1

nqf1 = 8
nqf2 = 8
nqf3 = 1
mp_mesh_k = .true.
nk1 = 8
nk2 = 8
nk3 = 1

nq1 = 8
nq2 = 8
nq3 = 1

/
10 cartesian
0.000000000 0.000000000 0.000000000 1.000000000
0.072952332 0.126357145 0.000000000 1.000000000
0.145904663 0.252714290 0.000000000 1.000000000
0.218856995 0.379071435 0.000000000 1.000000000
-0.291809327 -0.505428580 0.000000000 1.000000000
0.218856995 0.126357145 0.000000000 1.000000000
0.291809327 0.252714290 0.000000000 1.000000000
0.364761658 0.379071435 0.000000000 1.000000000
0.437713990 0.252714290 0.000000000 1.000000000
0.510666322 0.379071435 0.000000000 1.000000000

As followed by Pb Tutorial
--

&inputepw
prefix = 'NbSe2',
amass(1) = 92.91,
amass(2) = 78.96,
outdir = '/scratch/03972/konda16/EPW/Se/0.24/epw/'

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

epwwrite = .true.
epwread = .false.

nbndsub = 13
efermi_read = .true.
fermi_energy= -2.3624
wannierize = .true.
num_iter = 500
dis_win_min = -3.0
dis_froz_min = -2.2
dis_froz_max = 1.0
dis_win_max = 5.0

proj(1) = 'Nb:d'
proj(2) = 'Se:l=0;l=1'
wdata(1) = 'bands_plot = .true.'
wdata(2) = 'begin kpoint_path'
wdata(3) = 'G 0.00 0.00 0.00 M 0.50 0.00 0.00'
wdata(4) = 'M 0.50 0.00 0.00 K 0.33 0.33 0.00'
wdata(5) = 'K 0.33 0.33 0.00 G 0.00 0.00 0.00'
wdata(6) = 'end kpoint_path'
wdata(7) = 'bands_plot_format = xmgr'
wdata(8) = 'guiding_centres = TRUE '

iverbosity = 2

elinterp = .true.
phinterp = .true.
system_2d = .true.

tshuffle2 = .true.
tphases = .false.

elecselfen = .false.
phonselfen = .true.

parallel_k = .true.
parallel_q = .false.


fsthick = 2.0 ! eV
eptemp = 0 ! K
degaussw = 0.50 ! eV

a2f = .true.

dvscf_dir = '../phonons/save'


nkf1 = 64
nkf2 = 64
nkf3 = 1

nqf1 = 64
nqf2 = 64
nqf3 = 1

nk1 = 8
nk2 = 8
nk3 = 1

nq1 = 8
nq2 = 8
nq3 = 1

/
10 cartesian
0.000000000 0.000000000 0.000000000 1.000000000
0.072952332 0.126357145 0.000000000 1.000000000
0.145904663 0.252714290 0.000000000 1.000000000
0.218856995 0.379071435 0.000000000 1.000000000
-0.291809327 -0.505428580 0.000000000 1.000000000
0.218856995 0.126357145 0.000000000 1.000000000
0.291809327 0.252714290 0.000000000 1.000000000
0.364761658 0.379071435 0.000000000 1.000000000
0.437713990 0.252714290 0.000000000 1.000000000
0.510666322 0.379071435 0.000000000 1.000000000

with Regards
S. Appalakondaiah

[roxana]

Hi,

I spotted two possible problems in your output for MgB2.

1) temp( 1) = 0.0000 K

The temperature can be small, close to 0.0, but it cannot be exactly 0.0. Was the lowest temperature in the input file set to 0.0?

2) Total number of frequency points nsiw ( 1 ) = ******
Cutoff frequency wscut = 0.0000

This error appears since the cutoff frequency in the Matsubara equations appears to be set to 0.0

Did you try to run the MgB2 tutorial without making any changes to it? Do you have any errors in that case?

Best,
Roxana

[appalakondaiah]

Dear Roxana,

Thank you for quick reply

In the input, I consider eptemp as 0. So, I consider tempmin and tempmax should between the 0 and Tc values. Now I changed those values and testing. Continuing the previous doubt, my Tc and lambda values are largely varying by following lead and MgB2 tutorials. It is more puzzling me..

Yes..I did the MgB2 without any errors with low k-mesh and q-points..So, I did't verify the plots for cross check!!

with regards
S. Appalakondaiah