EPW Forum

I am using QE/6.3 and I want to use exclude_bands options from the wannier. I come across the following errors

Error: dis_spheres_first_wann is larger than num_bands-num_wann+1
Error: examine the output/error file for details

I have read the previous posts on this error message "http://epwforum.uk/viewtopic.php?f=6&t=13" and tried the same. But it did not work.

I do the same calculations using wannier90.x and its working but plugging in same parameters in the epw.in, ends up with the above error.

I calculate 60 bands in nscf.in and want to skip 1-28 bands and wannierize 14 bands in epw.in
on skipping 28 bands, 29th band should be the 1st band right? the default value of dis_spheres_first_wann is 1 and i am not specifying any value for that.

Here is the input file
--
&inputepw
prefix = 'cdte'
amass(1) = 112.411,
amass(2) = 127.600,
outdir = './'

iverbosity = 3
restart = .true.
restart_freq = 5000

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

epwwrite = .true.
epwread = .false.

max_memlt = 8.0

nbndsub = 14
nbndskip = 28

kmaps = .false.
! eig_read = .true.

wannierize = .true. !!!!!!!!!!!!!!!
num_iter = 8000
iprint = 2
dis_win_max = 25.0
dis_win_min = -7.00
dis_froz_min = -7.0
dis_froz_max= 2.50

proj(1) = 'random'

wdata(1) = 'bands_plot = true'
wdata(2) = 'begin kpoint_path'
wdata(3) = 'G 0.000 0.000 0.000 X 0.000 0.500 0.500'
wdata(4) = 'X 0.000 0.500 0.500 A 0.500 0.500 0.000'
wdata(5) = 'A 0.500 0.500 0.000 Y 0.000 0.500 0.000'
wdata(6) = 'Y 0.000 0.500 0.000 G 0.000 0.000 0.000'
wdata(7) = 'G 0.000 0.000 0.000 A 0.500 0.500 0.000'
wdata(8) = 'end kpoint_path'
wdata(9) = 'num_print_cycles = 50'
wdata(10)= 'dis_conv_tol = 1.0E-8' !!!!!!!!!!!!!!!!!!!!!!!!!!!!
wdata(11)= 'dis_mix_ratio = 0.6'
wdata(12)= 'dis_num_iter = 8000'
wdata(13) = 'conv_window = 2'
wdata(15) = 'conv_tol = 1.0E-8'!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
wdata(16) = 'exclude_bands = 1-28'
wdata(17) = 'guiding_centers = true'
! wdata(18) = 'dis_spheres_first_wann = 3'


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


eptemp = 00 ! K (same as PRB 76, 165108)
degaussw = 0.025 ! eV

dvscf_dir = '../single_phonon_so/save'
filukk = './cdte.ukk'


nk1 = 6
nk2 = 8
nk3 = 1

nq1 = 6
nq2 = 8
nq3 = 1
/
20 cartesian
0.0000000 0.0000000 0.0000000 0.0208333
0.0000000 0.1729437 0.0000000 0.0416667
0.0000000 0.3458873 0.0000000 0.0416667
.
.
.

Just wondering if exclude_bands option in epw is tested for any system or not? If yes, Could you please provide the reference? Because I don't see any in the example files.

Best wishes,

Hi,

The new exclude_bands feature of EPW requires a small modification of the wannier90 code directly.

We have included those modification in the development version of wannier90 on GitHub https://github.com/wannier-developers/wannier90. Therefore, to make this work you need to download the development version of Wannier90.

Note that there is also a skipband feature in EPW which doesn't require any change in wannier90.

In case you decide to use the new EPW feature with the development version on wannier90, it needs to be done in the following way:

nbndsub = 4
nbndskip = 5
bands_skipped = 'exclude_bands = 1:5'

where the number of excluded bands should be smaller or equal to nbndskip. In the case above nbndsub=4 wannier functions, and the first 5 bands were excluded from wannierization.

Best,
Roxana

Dear Roxana,

Thank you very much it worked.

Best wishes,