[Wannier] MLWFs for topological insulator

[Jianpeng Liu]

Hi Sheleon

First, the physically important orbitals in Bi2Se3 should be Bi 6p and Se
4p, the s orbitals are very flat and deep in valence bands. If all the p
orbitals are included, there should be 15 Wannier functions without SOC.
Second, I suspect 4x4x4 k-mesh is not enough for Bi2Se3, it may lead to
artificial dispersions in the bandstructure. From my experience, even if
you only use simple projections onto all the p orbitals (without
minimization procedure), the interpolated bandstructure is good enough for
Bi2Se3, and the spread functional is reasonbally small.

Good luck.

best,
Jianpeng
> Hi,
> Rencently, i am using wannier90 to interplot the bandstructure of
> topolocical insulator (i.e Bi2Se3). However I find it is very hard to
> construct the MLWF for this material.  i have tried various initial
> projections, but the MLWF never seem to be converged. Then i read the
> thread about the HgTe topological insulator and read the papers Ivo
> suggested. However it is still hard for me to get some clue for
> construct the correct input for wannier90. The following is my basic
> input for Bi2Se3, can anyone guide me the parameters i need to obtain
> the MLWFs for Bi2Se3?
> ###################################
> postproc_setup = .true.   !used to write .nnkp file at first run
> num_iter = 10000
>
> !comment out for first run, uncomment for stand-alone wannier90 runs
> ! to improve wannier convergence
> !restart = wannierise
>
> ! for band plotting
> bands_plot = .true.
> begin kpoint_path
> Z 0.00000  0.00000 0.0000 G 0.50000  0.50000 0.5000
> G 0.50000  0.50000 0.5000 F 0.50000  0.00000 0.5000
> F 0.50000  0.00000 0.5000 G 0.00000  0.00000 0.0000
> G 0.00000  0.00000 0.0000 L 0.00000  0.50000 0.0000
> end kpoint_path
>
> iprint = 3
>
> num_wann = 14
> num_bands = 25  !avoids breaking up degenerate groups on k-point mesh
> exclude_bands = 15-25
>
> begin projections
> Bi:s
> Se:sp3
> end projections
>
> mp_grid = 4  4 4
> ..........
> #############################3
> Any suggestion will be appreciate.
>
>
>
> Sheleon
>
> _______________________________________________
> Wannier mailing list
> Wannier at quantum-espresso.org
> http://www.democritos.it/mailman/listinfo/wannier
>