[Wannier] Projections

[Ghosh, Soham Subhra]

Dear Wannier90 users,

I am a new user of Wannier90. I have two questions, and I will be very thankful if you can help me out.

I am trying to find MLWFs for the cuprate La4Ba2Cu2O10. A DFT LDA calculation shows (using the Vienna-Ab-Initio Simulation package) that it has 2 narrow  bands around the Fermi level, with a dispersion of only a few meV. They are well separated from all the other bands. My axes are along the lattice vectors of the SC cell and the Cu-O planes are at 45 degrees to the walls of the cell.

What I understand from the site-and-band projected DOS (in VASP) is that each of the two bands  is the sum of antibonding Cu-dxy and Cu-dz2-r2. There is one band per copper atom. Both Cu-dxy and Cu-dz2-r2 have two peaks, one at Fermi energy and one significantly below. Is there a way to incorporate that in my initial projections? For my 2 wannier functions, wannier90 allows only specific values of 'l' and 'm' as initial projection. The only projection that converges is Cu-dz2.


My second question is about the use of narrow gaussian states centered at one of the main lobes of the Cu-d contribution as projection. Is that possible in Wannier90? As a first step of my calculation, I am trying to replicate the MLWFs in existing literature (PRL 89,16(2002)) where the use of this specific projection is quoted.


I am copying below my .win file (without the k-point list). Delta spread becomes ~10E-11 only after 180 odd steps. The program does not converge below Delta-spread ~10E-02 for most other values of trial_step, and for any other projection. Energy from VASP itself is well-converged.
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exclude_bands = 1-72,75-160
num_wann = 2

begin projections
c=0.00,3.42,2.93:dz2
c=3.42,0.00,2.93:dz2
end projections

num_iter = 200
guiding_centres = TRUE
trial_step = 1.9

begin unit_cell_cart
     6.8447000     0.0000000     0.0000000
     0.0000000     6.8447000     0.0000000
     0.0000000     0.0000000     5.8637000
end unit_cell_cart

begin atoms_cart
La       1.1964536     4.6188036     0.0000000
La       2.2258964     1.1964536     0.0000000
La       5.6482464     2.2258964     0.0000000
La       4.6188036     5.6482464     0.0000000
Ba       0.0000000     0.0000000     2.9318500
Ba       3.4223500     3.4223500     2.9318500
Cu       0.0000000     3.4223500     2.9318500
Cu       3.4223500     0.0000000     2.9318500
O        0.0000000     0.0000000     0.0000000
O        3.4223500     3.4223500     0.0000000
O        2.4818882     5.9042382     1.5509486
O        2.4818882     5.9042382     4.3127514
O        0.9404618     2.4818882     1.5509486
O        0.9404618     2.4818882     4.3127514
O        4.3628118     0.9404618     1.5509486
O        4.3628118     0.9404618     4.3127514
O        5.9042382     4.3628118     1.5509486
O        5.9042382     4.3628118     4.3127514
end atoms_cart

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

Thank a lot you for your time.

Regards,
Soham.

Soham S. Ghosh
Graduate Student
Department of Physics,
Florida State University

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