Error in routine mix_broyden(1) :factorization

[eliephys78]

Dear,

I am still having problems calculating the superconducting gap and Tc using The Eliashberg formalism. From the McMillan Dynes formula , I expect the superconducting temperature to be ~2.9K which was estimated using EPW. I have run the isotropic Eliashberg calculation for temps(1)=0.9 and increased it to 1.1K , which are not very small temperatures or temperatures close to Tc, but I am still getting an error:

Finish reading a2f file

Electron-phonon coupling strength = 0.0000000

Estimated Allen-Dynes Tc = NaN K for muc = 0.10000

Estimated w_log in Allen-Dynes Tc = NaN meV

Estimated BCS superconducting gap = NaN meV

temp( 1) = 1.10000 K

Solve isotropic Eliashberg equations on imaginary-axis

Total number of frequency points nsiw( 1) = 1679
Cutoff frequency wscut = 1.0003

iter ethr znormi deltai [meV]
1 NaN NaN NaN
2 NaN NaN NaN
3 NaN NaN NaN
4 NaN NaN NaN

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine mix_broyden (1):
factorization
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Any help is appreciated. the input file is :


outdir='/',
dvscf_dir ='/'

elph = .true.
kmaps = .false.
epbwrite = .true.
epbread = .false.
epwwrite = .true.
epwread = .false.
ephwrite=.true.
wannierize=.true.
nbndsub=14
num_iter=500
bands_skipped='exclude_bands=1,2,17,40'
max_memlt=5
!dis_froz_min = -10.0d0
!dis_froz_max = 0.0d0
proj(1)=''
proj(2)=''
proj(3)=''
proj(4) =''
system_2d=.true.
wscut=1.0
efermi_read=.true.
fermi_energy= -1.5629

etf_mem=1

wdata(1) ='search_shells=30'
wdata(2) ='bands_plot =.true.'
wdata(3) ='begin kpoint_path'
wdata(4)='G 0.000000 0.000000 0.000000 K 0.3333333 0.3333333 0.0000000'
wdata(5)='K 0.3333333 0.3333333 0.000000 M 0.5000000 0.0000000 0.0000000'
wdata(6)='M 0.5000000 0.0000000 0.000000 G 0.000000 0.000000 0.0000000'
wdata(7)='end kpoint_path'

elecselfen = .false.
phonselfen = .false.
a2f = .false.

eliashberg=.true.
liso=.true.
limag=.true.
lpade=.true.
muc=0.1
nsiter=4000
temps(1)=1.1
temps(2)=1.3
temps(3)=1.6
temps(4)=1.9
temps(5)=2.2
temps(6)=2.5
temps(7)=2.8
fsthick = 7 ! eV
degaussw = 0.005 ! eV
iverbosity=0

mp_mesh_k=.true.

nkf1 = 50
nkf2 = 50
nkf3 = 1

nqf1 = 50
nqf2 = 50
nqf3 = 1


nk1 = 36
nk2 = 36
nk3 = 1

nq1 = 12
nq2 = 12
nq3 = 1
/
74 cartesian

Regards

[roxana]

Hi,

I just noticed that the e-ph coupling strength in your output file is zero. It appears that something went wrong when reading a2f file. So check that the is correct.

"Electron-phonon coupling strength = 0.0000000"

Best,
Roxana

[hlee]

Dear eliephys78:

Could you let me know the total number of bands for the disentanglement for Wannierization in your calculation?

Code: Select all

bands_skipped='exclude_bands=1,2,17,40'

The excluded bands should consist of one or two contiguous blocks of bands (lowest or highest).
If you want to exclude the band groups composed of 1-2 bands and 17-40 bands, you should use the following input:

Code: Select all

bands_skipped='exclude_bands=1,2,17-40'

Lastly, I think that 2D treatment is currently not supported.

Code: Select all

system_2d=.true.

Sincerely,

H. Lee

[eliephys78]

Dear Drs. Lee and Roxana,

Thanks for your messages.

Dr. Roxana, i will check that.

Dr. Lee, indeed the exclude bands flag should have been 1,2,17-40. Regarding the system_2d flag, I have been using it to compute EPW for some 2D structures I am working on.. I haven't got any errors. So I thought there was no problem with that.

I will correct the potential errors and see if this works. Once again, many thanks

Regards

[hlee]

Dear eliephys78:

Regarding the 2D treatment in EPW:
I think that you already checked it, but if it is not the case, please check the post at viewtopic.php?f=3&t=1311 .

Sincerely,

H. Lee

[eliephys78]

Dear Dr. Lee,

Thanks for your message. I have checked this post last year. However what got me confused is the flag system_2d=.true. in the input (Documentation)

"system_2d

Default

.false.

Description

If .true. the system is two-dimensional (vaccum is in z-direction) and the k and q meshes are defined in the xy-plane."

which kind of gave me the wrong impression that EPW does work for 2D and one does not have to sample along the z-direction.

Regards