# RAD-tools - Sandbox (mainly condense matter plotting).
# Copyright (C) 2022-2024 Andrey Rybakov
#
# e-mail: anry@uv.es, web: rad-tools.org
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
r"""
General 3D lattice.
"""
import numpy as np
from scipy.spatial import Voronoi
import radtools.crystal.cell as Cell
from radtools.crystal.bravais_lattice.hs_points import (
BCC_hs_points,
BCT_hs_points,
CUB_hs_points,
FCC_hs_points,
HEX_hs_points,
MCL_hs_points,
MCLC_hs_points,
ORC_hs_points,
ORCC_hs_points,
ORCF_hs_points,
ORCI_hs_points,
RHL_hs_points,
TET_hs_points,
TRI_hs_points,
)
from radtools.crystal.bravais_lattice.standardize import standardize_cell
from radtools.crystal.bravais_lattice.variations import (
BCT_variation,
MCLC_variation,
ORCF_variation,
RHL_variation,
TRI_variation,
)
from radtools.crystal.constants import (
BRAVAIS_LATTICE_NAMES,
DEFAULT_K_PATHS,
HS_PLOT_NAMES,
PEARSON_SYMBOLS,
REL_TOL,
TRANSFORM_TO_CONVENTIONAL,
)
from radtools.crystal.identify import lepage
from radtools.crystal.kpoints import Kpoints
from radtools.geometry import angle, volume
__all__ = ["Lattice"]
[docs]
class Lattice:
r"""
General 3D lattice.
When created from the cell orientation of the cell is respected,
however the lattice vectors may be renamed with respect to [1]_.
Creation may change the angles and the lengths of the cell vectors.
It preserve the volume, right- or left- handedness, lattice type and variation
of the cell.
The lattice vector`s lengths are preserved as a set.
The angles between the lattice vectors are preserved as a set with possible
changes of the form: :math:`angle \rightarrow 180 - angle`.
The returned cell may not be the same as the input one, but it is translationally
equivalent.
Lattice can be created in a three alternative ways:
.. doctest::
>>> import radtools as rad
>>> l = rad.Lattice(cell = [[1, 0, 0], [0, 1, 0], [0, 0, 1]])
>>> l = rad.Lattice(a1 = [1,0,0], a2 = [0,1,0], a3 = [0,0,1])
>>> l = rad.Lattice(a=1, b=1, c=1, alpha=90, beta=90, gamma=90)
Parameters
----------
cell : (3, 3) |array_like|_
Unit cell, rows are vectors, columns are coordinates.
a1 : (3,) |array_like|_
First vector of unit cell (cell[0]).
a2 : (3,) |array_like|_
SEcond vector of unit cell (cell[1]).
a3 : (3,) |array_like|_
Third vector of unit cell (cell[2]).
a : float, default=1
Length of the :math:`a_1` vector.
b : float, default=1
Length of the :math:`a_2` vector.
c : float, default=1
Length of the :math:`a_3` vector.
alpha : float, default=90
Angle between vectors :math:`a_2` and :math:`a_3`. In degrees.
beta : float, default=90
Angle between vectors :math:`a_1` and :math:`a_3`. In degrees.
gamma : float, default=90
Angle between vectors :math:`a_1` and :math:`a_2`. In degrees.
standardize : bool, default True
Whether to standardize the cell.
The consistence of the predefined k paths is not guaranteed in the cell is not unified.
Attributes
----------
eps_rel : float, default 1e-4
Relative error for the :ref:`library_lepage` algorithm.
References
----------
.. [1] Setyawan, W. and Curtarolo, S., 2010.
High-throughput electronic band structure calculations: Challenges and tools.
Computational materials science, 49(2), pp.299-312.
"""
def __init__(self, *args, standardize=True, **kwargs) -> None:
self._eps_rel = REL_TOL
self._cell = None
self._type = None
self._kpoints = None
if "cell" in kwargs:
cell = kwargs["cell"]
elif "a1" in kwargs and "a2" in kwargs and "a3" in kwargs:
cell = np.array([kwargs["a1"], kwargs["a2"], kwargs["a3"]])
elif (
"a" in kwargs
and "b" in kwargs
and "c" in kwargs
and "alpha" in kwargs
and "beta" in kwargs
and "gamma" in kwargs
):
cell = Cell.from_params(
kwargs["a"],
kwargs["b"],
kwargs["c"],
kwargs["alpha"],
kwargs["beta"],
kwargs["gamma"],
)
elif len(args) == 1:
cell = np.array(args[0])
elif len(args) == 3:
cell = np.array(args)
elif len(args) == 6:
a, b, c, alpha, beta, gamma = args
cell = Cell.from_params(a, b, c, alpha, beta, gamma)
elif len(args) == 0 and len(kwargs) == 0:
cell = np.eye(3)
else:
raise ValueError(
"Unable to identify input parameters. "
+ "Supported: cell ((3,3) array_like), "
+ "or a1, a2, a3 (each is an (3,) array_like), "
+ "or a, b, c, alpha, beta, gamma (floats)."
)
self.fig = None
self.ax = None
self._set_cell(cell, standardize=standardize)
# Primitive cell parameters
@property
def cell(self):
r"""
Unit cell of the lattice.
Notes
-----
In order to rotate the cell with an arbitrary rotation matrix :math:`R` use the syntax:
.. code-block:: python
rotated_cell = cell @ R.T
Transpose is required, since the vectors are stored as rows.
Returns
-------
cell : (3, 3) :numpy:`ndarray`
Unit cell, rows are vectors, columns are coordinates.
"""
if self._cell is None:
raise AttributeError(f"Cell is not defined for lattice {self}")
return self._cell
# For the child`s overriding
def _set_cell(self, new_cell, standardize=True):
try:
new_cell = np.array(new_cell)
except:
raise ValueError(f"New cell is not array_like: {new_cell}")
if new_cell.shape != (3, 3):
raise ValueError(f"New cell is not 3 x 3 matrix.")
self._cell = new_cell
# Reset type
self._type = None
# Standardize cell
if standardize:
self._cell = standardize_cell(
self._cell, self.type(), rtol=self.eps_rel, atol=self.eps
)
@cell.setter
def cell(self, new_cell):
self._set_cell(new_cell)
@property
def a1(self):
r"""
First lattice vector :math:`\vec{a}_1`.
Returns
-------
a1 : (3,) :numpy:`ndarray`
First lattice vector :math:`\vec{a}_1`.
"""
return self.cell[0]
@property
def a2(self):
r"""
Second lattice vector :math:`\vec{a}_2`.
Returns
-------
a2 : (3,) :numpy:`ndarray`
Second lattice vector :math:`\vec{a}_2`.
"""
return self.cell[1]
@property
def a3(self):
r"""
Third lattice vector :math:`\vec{a}_3`.
Returns
-------
a3 : (3,) :numpy:`ndarray`
Third lattice vector :math:`\vec{a}_3`.
"""
return self.cell[2]
@property
def a(self):
r"""
Length of the first lattice vector :math:`\vert\vec{a}_1\vert`.
Returns
-------
a : float
"""
return np.linalg.norm(self.cell[0])
@property
def b(self):
r"""
Length of the second lattice vector :math:`\vert\vec{a}_2\vert`.
Returns
-------
b : float
"""
return np.linalg.norm(self.cell[1])
@property
def c(self):
r"""
Length of the third lattice vector :math:`\vert\vec{a}_3\vert`.
Returns
-------
c : float
"""
return np.linalg.norm(self.cell[2])
@property
def alpha(self):
r"""
Angle between second and third lattice vector.
Returns
-------
angle : float
In degrees
"""
return angle(self.a2, self.a3)
@property
def beta(self):
r"""
Angle between first and third lattice vector.
Returns
-------
angle : float
In degrees
"""
return angle(self.a1, self.a3)
@property
def gamma(self):
r"""
Angle between first and second lattice vector.
Returns
-------
angle : float
In degrees
"""
return angle(self.a1, self.a2)
@property
def unit_cell_volume(self):
r"""
Volume of the unit cell.
Returns
-------
volume : float
Unit cell volume.
"""
return volume(self.a1, self.a2, self.a3)
@property
def parameters(self):
r"""
Return cell parameters.
:math:`(a, b, c, \alpha, \beta, \gamma)`
Returns
-------
a : float
b : float
c : float
alpha : float
beta : float
gamma : float
"""
return self.a, self.b, self.c, self.alpha, self.beta, self.gamma
# Conventional cell parameters
@property
def conv_cell(self):
r"""
Conventional cell.
Returns
-------
conv_cell : (3, 3) :numpy:`ndarray`
Conventional cell, rows are vectors, columns are coordinates.
"""
return TRANSFORM_TO_CONVENTIONAL[self.type()] @ self.cell
@property
def conv_a1(self):
r"""
First vector of the conventional cell.
Returns
-------
conv_a1 : (3,) :numpy:`ndarray`
First vector of the conventional cell.
"""
return self.conv_cell[0]
@property
def conv_a2(self):
r"""
Second vector of the conventional cell.
Returns
-------
conv_a2 : (3,) :numpy:`ndarray`
Second vector of the conventional cell.
"""
return self.conv_cell[1]
@property
def conv_a3(self):
r"""
Third vector of the conventional cell.
Returns
-------
conv_a3 : (3,) :numpy:`ndarray`
Third vector of the conventional cell.
"""
return self.conv_cell[2]
@property
def conv_a(self):
r"""
Length of the first vector of the conventional cell.
Returns
-------
conv_a : float
Length of the first vector of the conventional cell.
"""
return np.linalg.norm(self.conv_a1)
@property
def conv_b(self):
r"""
Length of the second vector of the conventional cell.
Returns
-------
conv_b : float
Length of the second vector of the conventional cell.
"""
return np.linalg.norm(self.conv_a2)
@property
def conv_c(self):
r"""
Length of the third vector of the conventional cell.
Returns
-------
conv_c : float
Length of the third vector of the conventional cell.
"""
return np.linalg.norm(self.conv_a3)
@property
def conv_alpha(self):
r"""
Angle between second and third conventional lattice vector.
Returns
-------
angle : float
In degrees.
"""
return angle(self.conv_a2, self.conv_a3)
@property
def conv_beta(self):
r"""
Angle between first and third conventional lattice vector.
Returns
-------
angle : float
In degrees.
"""
return angle(self.conv_a1, self.conv_a3)
@property
def conv_gamma(self):
r"""
Angle between first and second conventional lattice vector.
Returns
-------
angle : float
In degrees.
"""
return angle(self.conv_a1, self.conv_a2)
@property
def conv_unit_cell_volume(self):
r"""
Volume of the conventional unit cell.
Returns
-------
volume : float
Unit cell volume.
"""
return volume(self.conv_a1, self.conv_a2, self.conv_a3)
@property
def conv_parameters(self):
r"""
Return conventional cell parameters.
:math:`(a, b, c, \alpha, \beta, \gamma)`
Returns
-------
a : float
b : float
c : float
alpha : float
beta : float
gamma : float
"""
return (
self.conv_a,
self.conv_b,
self.conv_c,
self.conv_alpha,
self.conv_beta,
self.conv_gamma,
)
# Reciprocal parameters
@property
def reciprocal_cell(self):
r"""
Reciprocal cell. Always primitive.
Returns
-------
reciprocal_cell : (3, 3) :numpy:`ndarray`
Reciprocal cell, rows are vectors, columns are coordinates.
"""
return Cell.reciprocal(self.cell)
@property
def b1(self):
r"""
First reciprocal lattice vector.
.. math::
\vec{b}_1 = \frac{2\pi}{V}\vec{a}_2\times\vec{a}_3
where :math:`V = \vec{a}_1\cdot(\vec{a}_2\times\vec{a}_3)`
Returns
-------
b1 : (3,) :numpy:`ndarray`
First reciprocal lattice vector :math:`\vec{b}_1`.
"""
return self.reciprocal_cell[0]
@property
def b2(self):
r"""
Second reciprocal lattice vector.
.. math::
\vec{b}_2 = \frac{2\pi}{V}\vec{a}_3\times\vec{a}_1
where :math:`V = \vec{a}_1\cdot(\vec{a}_2\times\vec{a}_3)`
Returns
-------
b2 : (3,) :numpy:`ndarray`
Second reciprocal lattice vector :math:`\vec{b}_2`.
"""
return self.reciprocal_cell[1]
@property
def b3(self):
r"""
Third reciprocal lattice vector.
.. math::
\vec{b}_3 = \frac{2\pi}{V}\vec{a}_1\times\vec{a}_2
where :math:`V = \vec{a}_1\cdot(\vec{a}_2\times\vec{a}_3)`
Returns
-------
b3 : (3,) :numpy:`ndarray`
Third reciprocal lattice vector :math:`\vec{b}_3`.
"""
return self.reciprocal_cell[2]
@property
def k_a(self):
r"""
Length of the first reciprocal lattice vector :math:`\vert\vec{b}_1\vert`.
Returns
-------
k_a : float
"""
return np.linalg.norm(self.b1)
@property
def k_b(self):
r"""
Length of the second reciprocal lattice vector :math:`\vert\vec{b}_2\vert`.
Returns
-------
k_b : float
"""
return np.linalg.norm(self.b2)
@property
def k_c(self):
r"""
Length of the third reciprocal lattice vector :math:`\vert\vec{b}_3\vert`.
Returns
-------
k_c : float
"""
return np.linalg.norm(self.b3)
@property
def k_alpha(self):
r"""
Angle between second and third reciprocal lattice vector.
Returns
-------
angle : float
In degrees.
"""
return angle(self.b2, self.b3)
@property
def k_beta(self):
r"""
Angle between first and third reciprocal lattice vector.
Returns
-------
angle : float
In degrees.
"""
return angle(self.b1, self.b3)
@property
def k_gamma(self):
r"""
Angle between first and second reciprocal lattice vector.
Returns
-------
angle : float
In degrees.
"""
return angle(self.b1, self.b2)
@property
def reciprocal_cell_volume(self):
r"""
Volume of the reciprocal cell.
.. math::
V = \vec{b}_1\cdot(\vec{b}_2\times\vec{b}_3)
Returns
-------
volume : float
Volume of the reciprocal cell.
"""
return volume(self.b1, self.b2, self.b3)
@property
def reciprocal_parameters(self):
r"""
Return reciprocal cell parameters.
:math:`(a, b, c, \alpha, \beta, \gamma)`
Returns
-------
a : float
b : float
c : float
alpha : float
beta : float
gamma : float
"""
return self.k_a, self.k_b, self.k_c, self.k_alpha, self.k_beta, self.k_gamma
# Lattice type routines and properties
@property
def eps(self):
r"""
Epsilon parameter.
Derived from :py:attr:`.eps_rel` as
.. math::
\epsilon = \epsilon_{rel}\cdot V^{\frac{1}{3}}
"""
return self.eps_rel * abs(self.unit_cell_volume) ** (1 / 3.0)
@property
def eps_rel(self):
r"""
Relative epsilon
Returns
-------
eps_rel : float
"""
return eps_rel
@eps_rel.setter
def eps_rel(self, new_value):
try:
self.eps_rel = float(new_value)
except ValueError:
raise ValueError("Not a float")
self._type = None
[docs]
def type(self, eps_rel=None):
r"""
Identify the lattice type.
Parameters
----------
eps_rel : float, optional
Relative error for the :ref:`library_lepage` algorithm.
Returns
-------
lattice_type : str
Bravais lattice type.
See Also
--------
lepage : Algoritm for the lattice type identification
variation : Variation of the lattice, if any.
"""
if self._type is None or eps_rel is not None:
if eps_rel is None:
eps_rel = self.eps_rel
lattice_type = lepage(
self.a,
self.b,
self.c,
self.alpha,
self.beta,
self.gamma,
eps_rel=eps_rel,
)
self._type = lattice_type
return self._type
@property
def variation(self):
r"""
Variation of the lattice, if any.
For the Bravais lattice with only one variation the :py:meth:`.Lattice.type` is returned.
Returns
-------
variation : str
Variation of the lattice.
Examples
--------
.. doctest::
>>> import radtools as rad
>>> l = rad.lattice_example("CUB")
>>> l.variation
'CUB'
.. doctest::
>>> import radtools as rad
>>> l = rad.lattice_example("BCT1")
>>> l.variation
'BCT1'
.. doctest::
>>> import radtools as rad
>>> l = rad.lattice_example("MCLC4")
>>> l.variation
'MCLC4'
See Also
--------
:py:meth:`.Lattice.type`
"""
lattice_type = self.type()
if lattice_type == "BCT":
result = BCT_variation(self.conv_a, self.conv_c)
elif lattice_type == "ORCF":
result = ORCF_variation(self.conv_a, self.conv_b, self.conv_c, self.eps)
elif lattice_type == "RHL":
result = RHL_variation(self.conv_alpha, self.eps)
elif lattice_type == "MCLC":
result = MCLC_variation(
self.conv_a,
self.conv_b,
self.conv_c,
self.conv_alpha,
self.k_gamma,
self.eps,
)
elif lattice_type == "TRI":
result = TRI_variation(self.k_alpha, self.k_beta, self.k_gamma, self.eps)
else:
result = lattice_type
return result
@property
def name(self):
r"""
Human-readable name of the Bravais lattice type.
Returns
-------
name : str
Name of the Bravais lattice type.
"""
return BRAVAIS_LATTICE_NAMES[self.type()]
@property
def pearson_symbol(self):
r"""
Pearson symbol.
Returns
-------
pearson_symbol : str
Pearson symbol of the lattice.
Raises
------
RuntimeError
If the type of the lattice is not defined.
Notes
-----
See: |PearsonSymbol|_
"""
return PEARSON_SYMBOLS[self.type()]
@property
def crystal_family(self):
r"""
Crystal family.
Returns
-------
crystal_family : str
Crystal family of the lattice.
Raises
------
ValueError
If the type of the lattice is not defined.
Notes
-----
See: |PearsonSymbol|_
"""
return self.pearson_symbol[0]
@property
def centring_type(self):
r"""
Centring type.
Returns
-------
centring_type : str
Centring type of the lattice.
Raises
------
ValueError
If the type of the lattice is not defined.
Notes
-----
See: |PearsonSymbol|_
"""
return self.pearson_symbol[1]
[docs]
def lattice_points(self, relative=False, reciprocal=False, normalize=False):
r"""
Compute lattice points
Parameters
----------
relative : bool, default False
Whether to return relative or absolute coordinates.
reciprocal : bool, default False
Whether to use reciprocal or real cell.
normalize : bool, default False
Whether to normalize corresponding vectors to have the volume equal to one.
Returns
-------
lattice_points : (N, 3) :numpy:`ndarray`
N lattice points. Each element is a vector :math:`v = (v_x, v_y, v_z)`.
"""
if reciprocal:
cell = self.reciprocal_cell
else:
cell = self.cell
if normalize:
cell /= volume(cell) ** (1 / 3.0)
lattice_points = np.zeros((27, 3), dtype=float)
for i in [-1, 0, 1]:
for j in [-1, 0, 1]:
for k in [-1, 0, 1]:
point = np.array([i, j, k])
if not relative:
point = point @ cell
lattice_points[9 * (i + 1) + 3 * (j + 1) + (k + 1)] = point
return lattice_points
[docs]
def voronoi_cell(self, reciprocal=False, normalize=False):
r"""
Computes Voronoi edges around (0,0,0) point.
Parameters
----------
reciprocal : bool, default False
Whether to use reciprocal or real cell.
Returns
-------
edges : (N, 2, 3) :numpy:`ndarray`
N edges of the Voronoi cell around (0,0,0) point.
Each elements contains two vectors of the points
of the voronoi vertices forming an edge.
vertices : (M, 3) :numpy:`ndarray`
M vertices of the Voronoi cell around (0,0,0) point.
Each element is a vector :math:`v = (v_x, v_y, v_z)`.
normalize : bool, default False
Whether to normalize corresponding vectors to have the volume equal to one.
"""
voronoi = Voronoi(
self.lattice_points(
relative=False, reciprocal=reciprocal, normalize=normalize
)
)
edges_index = set()
# Thanks ase for the idea. 13 - is the index of (0,0,0) point.
for rv, rp in zip(voronoi.ridge_vertices, voronoi.ridge_points):
if -1 not in rv and 13 in rp:
for j in range(0, len(rv)):
if (rv[j - 1], rv[j]) not in edges_index and (
rv[j],
rv[j - 1],
) not in edges_index:
edges_index.add((rv[j - 1], rv[j]))
edges_index = np.array(list(edges_index))
edges = np.zeros((edges_index.shape[0], 2, 3), dtype=voronoi.vertices.dtype)
for i in range(edges_index.shape[0]):
edges[i][0] = voronoi.vertices[edges_index[i][0]]
edges[i][1] = voronoi.vertices[edges_index[i][1]]
return edges, voronoi.vertices[np.unique(edges_index.flatten())]
@property
def kpoints(self) -> Kpoints:
r"""
Instance of :py:class:`.Kpoints` with the high symmetry points and path.
Notes
-----
When a new instance of the :py:class:`.Kpoints` is assigned to the lattice,
reciprocal vectors of the lattice are not updated. Reciprocal vectors of new kpoints
are not updated as well.
Returns
-------
kpoints : :py:class:`.Kpoints`
Instance of the :py:class:`.Kpoints` class.
See Also
--------
Kpoints : Class for the high symmetry points and path.
"""
if self._kpoints is None:
self._kpoints = Kpoints(self.b1, self.b2, self.b3)
if self.type() == "CUB":
hs_points = CUB_hs_points()
elif self.type() == "FCC":
hs_points = FCC_hs_points()
elif self.type() == "BCC":
hs_points = BCC_hs_points()
elif self.type() == "TET":
hs_points = TET_hs_points()
elif self.type() == "BCT":
hs_points = BCT_hs_points(self.variation, self.conv_a, self.conv_c)
elif self.type() == "ORC":
hs_points = ORC_hs_points()
elif self.type() == "ORCF":
hs_points = ORCF_hs_points(
self.variation, self.conv_a, self.conv_b, self.conv_c
)
elif self.type() == "ORCI":
hs_points = ORCI_hs_points(self.conv_a, self.conv_b, self.conv_c)
elif self.type() == "ORCC":
hs_points = ORCC_hs_points(self.conv_a, self.conv_b)
elif self.type() == "HEX":
hs_points = HEX_hs_points()
elif self.type() == "RHL":
hs_points = RHL_hs_points(self.variation, self.conv_alpha)
elif self.type() == "MCL":
hs_points = MCL_hs_points(self.conv_b, self.conv_c, self.conv_alpha)
elif self.type() == "MCLC":
hs_points = MCLC_hs_points(
self.variation,
self.conv_a,
self.conv_b,
self.conv_c,
self.conv_alpha,
)
elif self.type() == "TRI":
hs_points = TRI_hs_points(self.variation)
for point in hs_points:
if point == "S" and self.type() == "BCT":
self._kpoints.add_hs_point(
point, hs_points[point], label="$\\Sigma$"
)
elif point == "S1" and self.type() == "BCT":
self._kpoints.add_hs_point(
point, hs_points[point], label="$\\Sigma_1$"
)
else:
self._kpoints.add_hs_point(
point, hs_points[point], label=HS_PLOT_NAMES[point]
)
self._kpoints.path = DEFAULT_K_PATHS[self.variation]
return self._kpoints
@kpoints.setter
def kpoints(self, new_kpoints: Kpoints):
if not isinstance(new_kpoints, Kpoints):
raise ValueError(
f"New kpoints should be an instance of the Kpoints class. "
+ f"Got {type(new_kpoints)} instead."
)
self._kpoints = new_kpoints
