Fermi Surface

Generate and visualize Fermi surfaces from BXSF files. The Fermi surface mesh is generated in the frontend (JavaScript marching cubes); Python prepares the volumetric data and optional Brillouin-zone mesh via seekpath.

Requires the optional fermi-surface dependencies (includes seekpath):

pip install "weas-widget[fermi-surface]"

Here’s an example of how to use the add_fermi_surface_from_bxsf method:

[1]:

from weas_widget import WeasWidget
viewer = WeasWidget()
viewer.add_fermi_surface_from_bxsf(file_path="../../examples/copper.bxsf",
                                    clip_bz=True,
                                    brillouin_zone_options={"opacity": 0.1,
                                                            "color": "#34ebd8"})
viewer

/home/docs/checkouts/readthedocs.org/user_builds/weas-widget/envs/latest/lib/python3.11/site-packages/seekpath/brillouinzone/brillouinzone.py:26: UserWarning: `get_BZ` is deprecated, use the `BZ` class instead, to represent a brillouine zone. The faces and triangles can be accesses as attributes.
  warnings.warn(

[1]:

Parameters summary for add_fermi_surface_from_bxsf:

  • file_path: Path to the .bxsf file.

  • fermi_energy: Override the Fermi energy (default: use value in file).

  • drop_periodic: Drop the duplicated periodic end points (default: True).

  • clip_bz: Clip to the first Brillouin zone (default: True, requires seekpath).

  • show_bz: Add the Brillouin zone mesh (default: True).

  • show_reciprocal_axes: Add reciprocal axes vectors (default: True).

  • band_index: Render a single band by index (default: None).

  • combine_bands: Merge all Fermi-crossing bands into one mesh (default: False).

  • name: Mesh name override.

  • color: RGB list for the mesh color or hex color string.

  • opacity: Alpha channel applied to the mesh.

  • material_type: Material type for the mesh (default: "Standard").

  • brillouin_zone_options: Extra keyword arguments forwarded to add_brillouin_zone (e.g., custom color/opacity).

  • reciprocal_axes_options: Extra keyword arguments forwarded to add_reciprocal_axes.

Notes:

  • The Fermi surface mesh is generated in the frontend (JavaScript marching cubes).

  • If band_index is None, all Fermi-crossing bands are used.

  • If combine_bands=False, each band is added as a separate mesh.

  • A ValueError is raised when no Fermi-crossing bands are found.

You can customize the reciprocal axes and Brillouin-zone overlays when rendering a Fermi surface. For example, change the color and opacity of the Brillouin zone, and show the reciprocal axes with custom color and radius:

viewer.add_fermi_surface_from_bxsf(
    "copper.bxsf",
    clip_bz=True,
    show_bz=True,
    show_reciprocal_axes=True,
    brillouin_zone_options={"opacity": 0.1,
                            "color": "#34ebd8",
                            "show_edges": True},
    reciprocal_axes_options={"color": "#ff5733",
                            "radius": 0.05},
)