[Wannier] Wannier functions of molecular crystal

[Gianluca Giovannetti]

Dear All,

i`m calculating Wannier functions for a molecular crystal (sites are
molecule with C and H ions within each molecule).

i want to plot Wannier functions of the 4 bands at Fermi level.
the system is metallic.
these four bands come from HOMO and LUMO molecular states of the two
inequivalent molecules in the unit cell.

here it is my input file:

--------------------------------

num_wann        = 4
num_iter        = 2000

dis_num_iter    =  500

iprint = 3

!here we exclude all bands except the O2p bands
exclude_bands : 1-126,131-180

!bands_plot_project : 1,2,3,4

write_r2mn=.true.
hr_plot=.true.

kmesh_tol=0.00001

begin atoms_cart
ang
[......]
end atoms_cart

begin kpoint_path
G 0.00000000 0.00000000 0.00000000    M  0.50000000 0.00000000 0.00000000
M 0.50000000 0.00000000 0.00000000    X  0.50000000 0.50000000 0.00000000
X 0.50000000 0.50000000 0.00000000    G  0.50000000 0.00000000 0.50000000
G 0.50000000 0.00000000 0.50000000    Z  0.00000000 0.00000000 0.00000000
Z 0.00000000 0.00000000 0.00000000    R  0.50000000 0.50000000 0.00000000
R 0.50000000 0.50000000 0.00000000    A  0.50000000 0.00000000 0.50000000
A 0.50000000 0.00000000 0.50000000    Z  0.50000000 0.50000000 0.50000000
Z 0.50000000 0.50000000 0.50000000    C  0.50000000 0.00000000 0.00000000
C 0.50000000 0.00000000 0.00000000    F  0.50000000 0.50000000 0.00000000
end kpoint_path
bands_plot =T

!fermi_surface_plot = .true.

!To plot the WF
!wannier_plot = T
!wannier_plot_supercell = 2
!wannier_plot_list = 1 2 3 4
!restart = plot

guiding_centres = T

begin projections
random
end projections


begin unit_cell_cart
bohr
16.4538 0.000 0.000
0.000 0.000 -11.172
-1.18447 24.481 0.000
end unit_cell_cart

mp_grid : 8 8 8

begin kpoints
[...]
end kpoints


--------------------------------

However i get Wannier eigenvalues which are not exactly the same as the one
i have calculated Quantum espresso (the discrepancy is not big but finite at
some k-points).

My feeling is that the setting in the win file:

begin projections
random
end projections

is not really good as starting point.

Indeed the CONV is 1.0E-03.

HOMO and LUMO are localized on the molecules.

What is the best strategy in this case?

thank you in advance.

Gianluca
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