[Wannier] questions on VASPtowannier --1

[YANNING ZHANG]

Hi,

I am new to wannier90. I am now trying to repeat the results of bulk Si by using VASP+wannier. I recompiled vasp with wannier library, and then performed VASP with a wannier.win which is similar with your example03.

Here are the band structures I got. The black lines are from regular DFT calculation with PBE potential, the blue triangles are from wannier90_band.dat with a frozen energy window, and the green lines  are from wannier90 with no dis_froz_max specified and use_bloch_states = true. I thought that the latter, the green lines, should be similar with the "unconstrained projection" case in your review article (Rev. Mod. Phys, 2012, blue lines in fig.5). But it seems that the green lines are even in a better agreement with the PBE bands. So my first question is, what's problem?



Here is the wannier90.win file I used:

num_wann=8
num_bands=16 

Begin Projections
Si:sp3
End Projections

dis_win_max = 17.0d0
dis_froz_max= 6.4d0
dis_num_iter=1000

num_iter = 50
num_print_cycles = 10

guiding_centres=true

wannier_plot = true

# Bandstructure plot
restart         =  plot
fermi_energy = 6.1340 
fermi_surface_plot = true

#wvfn_formatted =  .true.
bands_plot      =  true
begin kpoint_path
L 0.50000  0.50000 0.5000 G 0.00000  0.00000 0.0000
G 0.00000  0.00000 0.0000 X 0.50000  0.00000 0.5000
X 0.50000  0.00000 0.5000 K 0.37500 -0.37500 0.0000
K 0.37500 -0.37500 0.0000 G 0.00000  0.00000 0.0000
end kpoint_path
bands_num_points 40
bands_plot_format gnuplot xmgrace

begin unit_cell_cart
     2.7150000     2.7150000     0.0000000
     0.0000000     2.7150000     2.7150000
     2.7150000     0.0000000     2.7150000
end unit_cell_cart

begin atoms_cart
Si       0.0000000     0.0000000     0.0000000
Si       1.3575000     1.3575000     1.3575000
end atoms_cart

mp_grid =     4     4     4

begin kpoints
     0.0000000     0.0000000     0.0000000
     0.2500000     0.0000000     0.0000000
........
     0.2500000    -0.5000000    -0.2500000
    -0.2500000     0.2500000    -0.5000000
end kpoints

And another one without 'dis_froz_max' is:

 num_wann =   8  ! set to NBANDS by VASP
 num_bands =  8

use_bloch_phases = T

num_iter = 1000
num_print_cycles = 10
iprint = 2
......


The second question is, I also tried to change the value of "dis_froz_max", from 9.0 to 3.0, but seems that the band was changed only slightly. Is this correct?




YANNING ZHANG

310A Rowland Hall
Department of Physics and Astronomy
University of California, Irvine

yanningz at uci.edu



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