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68 lines
2.0 KiB
68 lines
2.0 KiB
2 years ago
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"""
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Function-like objects that creates cubic clusters.
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"""
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import numpy as np
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from cmmde_cubic import FaceCenteredCubic
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from cmmde_compounds import L1_2
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def Octahedron(symbol, length, cutoff=0, latticeconstant=None, alloy=False):
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"""
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Returns Face Centered Cubic clusters of the octahedral class depending
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on the choice of cutoff.
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============================ =======================
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Type Condition
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============================ =======================
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Regular octahedron cutoff = 0
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Truncated octahedron cutoff > 0
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Regular truncated octahedron length = 3 * cutoff + 1
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Cuboctahedron length = 2 * cutoff + 1
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============================ =======================
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Parameters:
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symbol: string or sequence of int
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The chemical symbol or atomic number of the element(s).
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length: int
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Number of atoms on the square edges of the complete octahedron.
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cutoff (optional): int
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Number of layers cut at each vertex.
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latticeconstant (optional): float
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The lattice constant. If not given,
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then it is extracted form cmmde.data.
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alloy (optional): bool
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If true the L1_2 structure is used. Default is False.
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"""
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# Check length and cutoff
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if length < 1:
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raise ValueError("The length must be at least one.")
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if cutoff < 0 or length < 2 * cutoff + 1:
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raise ValueError(
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"The cutoff must fulfill: > 0 and <= (length - 1) / 2.")
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# Create cluster
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surfaces = [(1, 1, 1), (1, 0, 0)]
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if length % 2 == 0:
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center = np.array([0.5, 0.5, 0.5])
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layers = [length / 2, length - 1 - cutoff]
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else:
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center = np.array([0.0, 0.0, 0.0])
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layers = [(length - 1) / 2, length - 1 - cutoff]
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if not alloy:
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return FaceCenteredCubic(
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symbol, surfaces, layers, latticeconstant, center)
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else:
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return L1_2(symbol, surfaces, layers, latticeconstant, center)
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