NEW! Wannierisation inside WannierBerri

Now WannierBerri can construct wannier functions on its own. Bith disentanglement and localisation.

Wannierisation can be performed with both sitesym=True and frozen window (this feature is currently not available in Wannier90).

see examples in examples/wannierise+sitesym-Fe and examples/wannierise+sitesym-diamond

wannierise.wannierise(froz_min=inf, froz_max=-inf, num_iter=1000, conv_tol=1e-09, num_iter_converge=3, mix_ratio_z=0.5, mix_ratio_u=1, print_progress_every=10, sitesym=False, localise=True, kwargs_sitesym={}, init='amn', num_wann=None)

Performs disentanglement and maximal localization of the bands recorded in w90data. The disentanglement is done following the procedure described in Souza et al., PRB 2001. The localization is done following a simplified procedure, avoiding gradient descent of the spread functional.

At the end writes w90data.chk.v_matrix and sets w90data.wannierised = True

Parameters:

  • w90data (Wannier90data) – the data

  • froz_min (float) – lower bound of the frozen window

  • froz_max (float) – upper bound of the frozen window

  • num_iter (int) – maximal number of iterations.

  • conv_tol (float) – tolerance for convergence of the spread functional (in \(\mathring{\rm A}^{2}\))

  • num_iter_converge (int) – the convergence is achieved when the standard deviation of the spread functional over the num_iter_converge*print_progress_every iterations is less than conv_tol

  • mix_ratio_z (float) – 0 <= mix_ratio_z <=1 - mixing the Z matrix (disentanglement) from previous itertions. 1 for max speed, smaller values are more stable

  • mix_ratio_u (float) – 0 <= mix_ratio_u <=1 - mixing the U matrix (localization) from previous itertions. 1 for max speed, smaller values are more stable WARNING : u<1 at the moment may lead to non-convergence. It is recommended to use mix_ratio_u=1 for now.

  • print_progress_every – frequency to print the progress

  • sitesym (bool) – whether to use the site symmetry (Symmetry-adapted Wannier Functions). If True, the dmn attribute should be present in the w90data (either from pw2wannier90 or generated by wabnnierberri see DMN, from_irrep() and set_D_wann_from_projections()

  • localise (bool) – whether to perform the localization. If False, only disentanglement and roatation to projections are performed

  • kwargs_sitesym (dict) – additional the keyword arguments to be passed to the constructor of the Symmetrizer

  • init (str) – the initialization of the U matrix. “amn” for the current state, “random” for random initialization, “restart” for restarting from the previous state

  • num_wann (int) – the number of Wannier functions. Required for random initialization only without sitesymmetry

Returns:

w90data.chk.v_matrix – the optimized U matrices

Return type:

numpy.ndarray

Note

  • Also sets the following attributes of chk:
    • w90data.chk.v_matrixnumpy.ndarray

      the optimized U matrices

    • w90data.wannierisedbool

      True

    • w90data.chk._wannier_centersnumpy.ndarray (nW,3)

      the centers of the Wannier functions

    • w90data.chk._wannier_spreadsnumpy.ndarray (nW)

      the spreads of the Wannier functions

  • If the outer window is needed, use apply_window() of the Wannier90data before calling this function.

  • The function is not parallelized yet

  • Disentanglement and localization are done in the irreducible BZ (if sitesym=True) and then symmetrized to the full BZ

  • Disentanglement and localization are done together, in the same loop. Therefore only one parameter num_iter is used for both

Example

# This tutorial shows how to generate a DMN file inside Wanier Berri code (without pw2wannier90)
# and then use it to generate a Wannier90 output.
# It may be used with any DFT code that is supported by IrRep (QE, VASP, AINIT, ...)
# the .dmn file is not needed before the calculation, it is generated on the fly

import wannierberri as wberri
from wannierberri.w90files import DMN
from irrep.bandstructure import BandStructure

# Create the dmn file
try:
   dmn_new = DMN("mydmn")
except:
      # see documentation of irrep for usage with other codes
   bandstructure = BandStructure(code='espresso', prefix='di', Ecut=100,
                              normalize=False)

   bandstructure.spacegroup.show()
   dmn_new = DMN(empty=True)
   dmn_new.from_irrep(bandstructure)
   pos = [[0,0,0],[0,0,1/2],[0,1/2,0],[1/2,0,0]]
   dmn_new.set_D_wann_from_projections(projections=[(pos, 's') ])
   dmn_new.to_w90_file("mydmn")

# Read the data from the Wanier90 inputs
w90data = wberri.w90files.Wannier90data(seedname='diamond')
w90data.set_file("dmn", dmn_new)

#Now disentangle with sitesym and frozen window (the part that is not implemented in Wanier90)
w90data.wannierise(
               froz_min=0,
               froz_max=4,
               num_iter=1000,
               conv_tol=1e-6,
               mix_ratio_z=1.0,
               print_progress_every=20,
               sitesym=True,
               localise=True,
               )

system = wberri.system.System_w90(w90data=w90data)

# Now do whatever you want with the system, as if it was created with Wannier90