cnncnnzh / topophonon

topoPhonon package is a python package that allows users to calculate topological properties (berry phase, berry curvature, wannier charge center evolution...), by building phonon tight binding model.

topoPhonon

topoPhonon is a python package that allows users to phononic calculate topological properties, by building phonon tight-binding model.

• Build tight-binding models from user's input, FORCE_CONSTANTS files or Phonopy API. The last method is much faster, but need to import Phonopy package and manually create phonopy.harmonic.dynamical_matrix.DynamicalMatrix object.
• Calculate berry phase, berry curvature, wannier charge center evolution around Weyl points from tight-binding model.
• Build slab/ribbon models for surface/edge.
• Plot 3d band surfaces.

Installation:

pip install topophonon

Basic usage:

Use one line of code to build tight-binding model:
model = read_from_files(path)
where the path should contain POSCAR, SPOSCAR and FORCE_CONSTANTS files.

From the model just built, build a slab model with multi layers along fin_dir:
model_2d = model.cut_piece(multi, fin_dir)
model_2d = model_2d.atom_projected_band(q_path, node_names)

Create a Topology object:
tp = Topology(model)
Plot the energy surfaces of band1 and band2 and find the degenerate points on z=0 plane:
model.plot_3d_band([band1, band2], center, xy_range)
Then plot wannier charge center evolution around center for band_indices:
tp.wcc_evol_sphere(band_indices, center)
and the berry curvature distribution on $k_i$=kz plane, where $k_i$ = $k_z, k_y, k_z$ if dirc = 0, 1, 2, respectively:
tp.berry_curvature_proj(band_indices, dirc, kz)

More examples can be found in runExamples.py file