# pymatgen.analysis.wulff module¶

This module define a WulffShape class to generate the Wulff shape from a lattice, a list of indices and their corresponding surface energies, and the total area and volume of the wulff shape,the weighted surface energy, the anisotropy and shape_factor can also be calculated. In support of plotting from a given view in terms of miller index.

The lattice is from the conventional unit cell, and (hkil) for hexagonal lattices.

If you use this code extensively, consider citing the following:

Tran, R.; Xu, Z.; Radhakrishnan, B.; Winston, D.; Persson, K. A.; Ong, S. P. (2016). Surface energies of elemental crystals. Scientific Data.

class WulffFacet(normal, e_surf, normal_pt, dual_pt, index, m_ind_orig, miller)[source]

Bases: object

Helper container for each Wulff plane.

class WulffShape(lattice, miller_list, e_surf_list, symprec=1e-05)[source]

Bases: object

Generate Wulff Shape from list of miller index and surface energies, with given conventional unit cell. surface energy (Jm^2) is the length of normal.

Wulff shape is the convex hull. Based on: http://scipy.github.io/devdocs/generated/scipy.spatial.ConvexHull.html

Process:
1. get wulff simplices
2. label with color
3. get wulff_area and other properties
debug(bool)
alpha
transparency
color_set
grid_off(bool)
axis_off(bool)
show_area
off_color
color of facets off wulff
structure
Structure object, input conventional unit cell (with H ) from lattice
miller_list
list of input miller index, for hcp in the form of hkil
hkl_list
modify hkill to hkl, in the same order with input_miller
e_surf_list
list of input surface energies, in the same order with input_miller
lattice
Lattice object, the input lattice for the conventional unit cell
facets
[WulffFacet] for all facets considering symm
dual_cv_simp
simplices from the dual convex hull (dual_pt)
wulff_pt_list
wulff_cv_simp
simplices from the convex hull of wulff_pt_list
on_wulff
list for all input_miller, True is on wulff.
color_area
list for all input_miller, total area on wulff, off_wulff = 0.
miller_area
($hkl$): area for all input_miller
Parameters: lattice – Lattice object of the conventional unit cell miller_list ([(hkl) – list of hkl or hkil for hcp e_surf_list ([float]) – list of corresponding surface energies symprec (float) – for recp_operation, default is 1e-5.
anisotropy

(float) Coefficient of Variation from weighted surface energy The ideal sphere is 0.

Type: Returns
area_fraction_dict

{hkl: area_hkl/total area on wulff}

Type: Returns (dict)
effective_radius

Radius of the Wulffshape when the Wulffshape is approximated as a sphere.

get_line_in_facet(facet)[source]

Returns the sorted pts in a facet used to draw a line

get_plot(color_set='PuBu', grid_off=True, axis_off=True, show_area=False, alpha=1, off_color='red', direction=None, bar_pos=(0.75, 0.15, 0.05, 0.65), bar_on=False, units_in_JPERM2=True, legend_on=True, aspect_ratio=(8, 8), custom_colors={})[source]

Get the Wulff shape plot.

Parameters: color_set – default is ‘PuBu’ grid_off (bool) – default is True axis_off (bool) – default is Ture show_area (bool) – default is False alpha (float) – chosen from 0 to 1 (float), default is 1 off_color – Default color for facets not present on the Wulff shape. direction – default is (1, 1, 1) bar_pos – default is [0.75, 0.15, 0.05, 0.65] bar_on (bool) – default is False legend_on (bool) – default is True aspect_ratio – default is (8, 8) ({(h,k,l} (custom_colors) – [r,g,b,alpha}): Customize color of each facet with a dictionary. The key is the corresponding Miller index and value is the color. Undefined facets will use default color site. Note: If you decide to set your own colors, it probably won’t make any sense to have the color bar on. (matplotlib.pyplot)
miller_area_dict

area_hkl on wulff}

Type: Returns {hkl
miller_energy_dict

surface energy_hkl}

Type: Returns {hkl
shape_factor

This is useful for determining the critical nucleus size. A large shape factor indicates great anisotropy. See Ballufi, R. W., Allen, S. M. & Carter, W. C. Kinetics

of Materials. (John Wiley & Sons, 2005), p.461
Returns: (float) Shape factor.
show(*args, **kwargs)[source]

Show the Wulff plot.

Parameters: *args – Passed to get_plot. **kwargs – Passed to get_plot.
surface_area

Total surface area of Wulff shape.

tot_corner_sites

Returns the number of vertices in the convex hull. Useful for identifying catalytically active sites.

tot_edges

Returns the number of edges in the convex hull. Useful for identifying catalytically active sites.

total_surface_energy

Total surface energy of the Wulff shape.

Returns: (float) sum(surface_energy_hkl * area_hkl)
volume

Volume of the Wulff shape

weighted_surface_energy

sum(surface_energy_hkl * area_hkl)/ sum(area_hkl)

Type: Returns
get_tri_area(pts)[source]

Given a list of coords for 3 points, Compute the area of this triangle.

Parameters: pts – [a, b, c] three points
hkl_tuple_to_str(hkl)[source]

Prepare for display on plots “(hkl)” for surfaces Agrs:

hkl: in the form of [h, k, l] or (h, k, l)