1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
"""
Function-like objects that creates cubic clusters.
"""
import numpy as np
from ase.cluster.cubic import FaceCenteredCubic
from ase.cluster.compounds import L1_2
def Octahedron(symbol, length, cutoff=0, latticeconstant=None, alloy=False):
"""
Returns Face Centered Cubic clusters of the octahedral class depending
on the choice of cutoff.
============================ =======================
Type Condition
============================ =======================
Regular octahedron cutoff = 0
Truncated octahedron cutoff > 0
Regular truncated octahedron length = 3 * cutoff + 1
Cuboctahedron length = 2 * cutoff + 1
============================ =======================
Parameters:
symbol: string or sequence of int
The chemical symbol or atomic number of the element(s).
length: int
Number of atoms on the square edges of the complete octahedron.
cutoff (optional): int
Number of layers cut at each vertex.
latticeconstant (optional): float
The lattice constant. If not given,
then it is extracted form ase.data.
alloy (optional): bool
If true the L1_2 structure is used. Default is False.
"""
# Check length and cutoff
if length < 1:
raise ValueError("The length must be at least one.")
if cutoff < 0 or length < 2 * cutoff + 1:
raise ValueError(
"The cutoff must fulfill: > 0 and <= (length - 1) / 2.")
# Create cluster
surfaces = [(1, 1, 1), (1, 0, 0)]
if length % 2 == 0:
center = np.array([0.5, 0.5, 0.5])
layers = [length / 2, length - 1 - cutoff]
else:
center = np.array([0.0, 0.0, 0.0])
layers = [(length - 1) / 2, length - 1 - cutoff]
if not alloy:
return FaceCenteredCubic(
symbol, surfaces, layers, latticeconstant, center)
else:
return L1_2(symbol, surfaces, layers, latticeconstant, center)
|
