Coverage for eminus/atoms.py: 98.10%
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« prev ^ index » next coverage.py v7.6.4, created at 2024-11-01 11:47 +0000
1# SPDX-FileCopyrightText: 2021 The eminus developers
2# SPDX-License-Identifier: Apache-2.0
3"""Atoms class definition."""
5import numbers
7import numpy as np
8from scipy.fft import next_fast_len
9from scipy.linalg import det, eigh, inv, norm
11from . import operators
12from .kpoints import KPoints
13from .logger import create_logger, get_level, log
14from .occupations import Occupations
15from .tools import center_of_mass, cutoff2gridspacing, inertia_tensor
16from .utils import atom2charge, BaseObject, molecule2list
19class Atoms(BaseObject):
20 """Atoms object that holds all system and cell parameters.
22 Args:
23 atom: Atom symbols.
25 A string can be given, e.g., with :code:`CH4` that will be parsed to
26 :code:`["C", "H", "H", "H", "H"]`. When calculating atoms one can directly provide the
27 charge, e.g., with :code:`Li-q3`.
28 pos: Atom positions.
30 Keyword Args:
31 ecut: Cut-off energy.
33 Defaults to 30 Eh (ca. 816 eV).
34 a: Cell size or vacuum size.
36 Floats will create a cubic unit cell. Defaults to a 20 a0 (ca. 10.5 A) cubic cell.
37 Scaled lattice vectors can be given to build a custom cell.
38 spin: Number of unpaired electrons.
40 This is the difference between the number of up and down electrons.
41 charge: Charge of the system.
42 unrestricted: Handling of spin.
44 :code:`False` for restricted, :code:`True` for unrestricted, and :code:`None` for
45 automatic detection.
46 center: Center the system inside the cell.
48 Aligns the geometric center of mass with the center of the call and rotates the system,
49 such that its geometric moment of inertia aligns with the coordinate axes. Can be one of
50 bool, "shift", and "rotate".
51 verbose: Level of output.
53 Can be one of "critical", "error", "warning", "info" (default), or "debug". An integer
54 value can be used as well, where larger numbers mean more output, starting from 0.
55 None will use the global logger verbosity value.
56 """
58 def __init__(
59 self,
60 atom,
61 pos,
62 ecut=30,
63 a=20,
64 spin=None,
65 charge=0,
66 unrestricted=None,
67 center=False,
68 verbose=None,
69 ):
70 """Initialize the Atoms object."""
71 # Set the input parameters (the ordering is important)
72 self._log = create_logger(self) #: Logger object.
73 self.verbose = verbose #: Verbosity level.
74 self.occ = Occupations() #: Occupations object.
75 self.atom = atom #: Atom symbols.
76 self.pos = pos #: Atom positions.
77 self.a = a #: Cell/Vacuum size.
78 self.ecut = ecut #: Cut-off energy.
79 self.center = center #: Enables centering the system in the cell.
80 self.charge = charge #: System charge.
81 self.spin = spin #: Number of unpaired electrons.
82 self.unrestricted = unrestricted #: Enables unrestricted spin handling.
83 self.kpts = KPoints("sc", self.a) #: KPoints object.
85 # Initialize other attributes
86 self.occ.fill() #: Fill states from the given input.
87 self.is_built = False #: Determines the Atoms object build status.
89 # ### Class properties ###
91 @property
92 def atom(self):
93 """Atom symbols."""
94 return self._atom
96 @atom.setter
97 def atom(self, value):
98 # Quick option to set the charge for single atoms
99 if isinstance(value, str) and "-q" in value:
100 atom, Z = value.split("-q")
101 self._atom = [atom]
102 self._Natoms = 1
103 self.Z = int(Z)
104 else:
105 # If a string, i.e., chemical formula is given convert it to a list of chemical symbols
106 if isinstance(value, str):
107 self._atom = molecule2list(value)
108 else:
109 self._atom = value
110 # Get the number of atoms and determine the charges
111 self._Natoms = len(self._atom)
112 self.Z = None
114 @property
115 def pos(self):
116 """Atom positions."""
117 return self._pos
119 @pos.setter
120 def pos(self, value):
121 # We need atom positions as a two-dimensional array
122 self._pos = np.atleast_2d(value)
123 if self.Natoms != len(self._pos):
124 msg = (
125 f"Mismatch between number of atoms ({self.Natoms}) and number of "
126 f"coordinates ({len(self._pos)})."
127 )
128 raise ValueError(msg)
129 # The structure factor changes when changing pos
130 self.is_built = False
132 @property
133 def ecut(self):
134 """Cut-off energy."""
135 return self._ecut
137 @ecut.setter
138 def ecut(self, value):
139 self._ecut = value
140 # Calculate the sampling from the cut-off energy
141 s = np.int64(norm(self.a, axis=0) / cutoff2gridspacing(value))
142 # Multiply by two and add one to match PWDFT.jl
143 s = 2 * s + 1
144 # Calculate a fast length to optimize the FFT calculations
145 self.s = [next_fast_len(i) for i in s]
146 # The cell discretization changes when changing s or ecut
147 self.is_built = False
149 @property
150 def a(self):
151 """Cell/Vacuum size."""
152 return self._a
154 @a.setter
155 def a(self, value):
156 # Build a cubic cell if a number or 1d-array is given
157 if np.asarray(value).ndim <= 1:
158 self._a = value * np.eye(3)
159 # Otherwise scaled cell vectors are given
160 else:
161 self._a = np.asarray(value)
162 # Update ecut and s if it has been set before
163 if hasattr(self, "ecut"):
164 self.ecut = self.ecut
165 # Calculate the unit cell volume
166 self._Omega = abs(det(self._a))
167 if hasattr(self, "kpts"):
168 self.kpts.a = self._a
169 # The cell changes when changing a
170 self.is_built = False
172 @property
173 def spin(self):
174 """Number of unpaired electrons."""
175 return self.occ.spin
177 @spin.setter
178 def spin(self, value):
179 self.occ.spin = value
181 @property
182 def charge(self):
183 """System charge."""
184 return self.occ.charge
186 @charge.setter
187 def charge(self, value):
188 self.occ.charge = value
190 @property
191 def unrestricted(self):
192 """Enables unrestricted spin handling."""
193 return self.occ.Nspin == 2
195 @unrestricted.setter
196 def unrestricted(self, value):
197 if value is None:
198 self.occ.Nspin = value
199 else:
200 self.occ.Nspin = value + 1
202 @property
203 def center(self):
204 """Enables centering the system in the cell."""
205 return self._center
207 @center.setter
208 def center(self, value):
209 if isinstance(value, str):
210 self._center = value.lower()
211 if self._center not in {"rotate", "shift", "recentered"}:
212 log.error(f"{self._center} is not a recognized center method.")
213 else:
214 self._center = value
215 # Do nothing when recentering
216 if self._center == "recentered":
217 return
218 # Center system such that the geometric inertia tensor will be diagonal
219 # Rotate before shifting!
220 if self._center is True or self._center == "rotate":
221 I = inertia_tensor(self.pos)
222 _, eigvecs = eigh(I)
223 self.pos = (inv(eigvecs) @ self.pos.T).T
224 # Shift system such that its geometric center of mass is in the center of the cell
225 if self._center is True or self._center == "shift":
226 com = center_of_mass(self.pos)
227 self.pos = self.pos - (com - np.sum(self.a, axis=0) / 2)
228 # The structure factor changes when changing pos
229 self.is_built = False
231 @property
232 def verbose(self):
233 """Verbosity level."""
234 return self._verbose
236 @verbose.setter
237 def verbose(self, value):
238 # If no verbosity is given use the global verbosity level
239 if value is None:
240 value = log.verbose
241 self._verbose = get_level(value)
242 self._log.verbose = self._verbose
244 # ### Class properties with a setter outside of the init method ###
246 @property
247 def f(self):
248 """Occupation numbers per state."""
249 return self.occ.f
251 @f.setter
252 def f(self, value):
253 # Pass through to the Occupations object
254 self.occ.f = value
256 @property
257 def s(self):
258 """Real-space sampling of the cell."""
259 return self._s
261 @s.setter
262 def s(self, value):
263 # Choose the same sampling for every direction if an integer is given
264 if isinstance(value, numbers.Integral):
265 value = value * np.ones(3, dtype=int)
266 self._s = np.asarray(value)
267 self._Ns = int(np.prod(self._s))
268 # The cell discretization changes when changing s
269 self.is_built = False
271 @property
272 def Z(self):
273 """Valence charge per atom."""
274 return self._Z
276 @Z.setter
277 def Z(self, value):
278 # Assume same charges for all atoms if an integer is given
279 if isinstance(value, numbers.Integral):
280 value = value * np.ones(self.Natoms, dtype=int)
281 elif isinstance(value, dict):
282 value = [value[ia] for ia in self.atom]
283 # Get the valence charges from the GTH files
284 elif value is None or isinstance(value, str):
285 value = atom2charge(self.atom, value)
286 self._Z = np.asarray(value)
287 if self.Natoms != len(self._Z):
288 msg = (
289 f"Mismatch between number of atoms ({self.Natoms}) and number of "
290 f"charges ({len(self._Z)})."
291 )
292 raise ValueError(msg)
293 # Get the number of calculated electrons and pass it to occ
294 self.occ.Nelec = np.sum(self._Z) - self.charge
296 # ### Read-only properties ###
298 @property
299 def Natoms(self):
300 """Number of atoms."""
301 return self._Natoms
303 @property
304 def Ns(self):
305 """Number of real-space grid points."""
306 return self._Ns
308 @property
309 def Omega(self):
310 """Unit cell volume."""
311 return self._Omega
313 @property
314 def r(self):
315 """Real-space sampling points."""
316 return self._r
318 @property
319 def active(self):
320 """Mask for active G-vectors."""
321 return self._active
323 @property
324 def G(self):
325 """G-vectors."""
326 return self._G
328 @property
329 def G2(self):
330 """Squared magnitudes of G-vectors."""
331 return self._G2
333 @property
334 def G2c(self):
335 """Truncated squared magnitudes of G-vectors."""
336 return self._G2c
338 @property
339 def Gk2(self):
340 """Squared magnitudes of G+k-vectors."""
341 return self._Gk2
343 @property
344 def Gk2c(self):
345 """Truncated squared magnitudes of G+k-vectors."""
346 return self._Gk2c
348 @property
349 def Sf(self):
350 """Structure factor per atom."""
351 return self._Sf
353 @property
354 def dV(self):
355 """Volume element to multiply when integrating field properties."""
356 return self.Omega / self._Ns
358 @property
359 def _atoms(self):
360 """Return the Atoms object itself."""
361 # This way we can access the object from Atoms and SCF classes with the same code
362 return self
364 # ### Class methods ###
366 def build(self):
367 """Build all parameters of the Atoms object."""
368 self.kpts.build()
369 self._sample_unit_cell()
370 self.occ.wk = self.kpts.wk # Pass the weights of k-points to the Occupations object
371 self.occ.fill()
372 self.is_built = True
373 return self
375 kernel = build
377 def recenter(self, center=None):
378 """Recenter the system inside the cell.
380 Keyword Args:
381 center: Point to center the system around.
382 """
383 com = center_of_mass(self.pos)
384 if center is None:
385 self.pos = self.pos - (com - np.sum(self.a, axis=0) / 2)
386 else:
387 center = np.asarray(center)
388 self.pos = self.pos - (com - center)
389 # Recalculate the structure factor since it depends on the atom positions
390 self._Sf = np.exp(1j * self.G @ self.pos.T).T
391 self._center = "recentered"
392 return self
394 def set_k(self, k, wk=None):
395 """Interface to set custom k-points.
397 Args:
398 k: k-point coordinates.
400 Keyword Args:
401 wk: k-point weights.
402 """
403 self.kpts.build()
404 self.kpts._k = np.atleast_2d(k)
405 if wk is None:
406 self.kpts._wk = np.ones(len(self.kpts._k)) / len(self.kpts._k)
407 else:
408 self.kpts._wk = np.asarray(wk)
409 self.kpts._Nk = len(self.kpts._wk)
410 self.kpts._kmesh = None
411 self.occ.wk = self.kpts.wk
412 self._sample_unit_cell()
413 return self
415 def clear(self):
416 """Initialize or clear parameters that will be built out of the inputs."""
417 self._r = None # Sample points in cell
418 self._G = None # G-vectors
419 self._G2 = None # Squared magnitudes of G-vectors
420 self._active = None # Mask for active G-vectors
421 self._G2c = None # Truncated squared magnitudes of G-vectors
422 self._Sf = None # Structure factor
423 self.is_built = False # Flag to determine if the object was built or not
424 return self
426 def _get_index_matrices(self):
427 """Build index matrices M and N to build the real and reciprocal space samplings.
429 The matrices are using C ordering (the last index is the fastest).
431 Returns:
432 Index matrices.
433 """
434 # Build index matrix M
435 # ms = np.arange(self._Ns)
436 # m1 = np.floor(ms / (self.s[2] * self.s[1])) % self.s[0]
437 # m2 = np.floor(ms / self.s[2]) % self.s[1]
438 # m3 = ms % self.s[2]
439 # M = np.column_stack((m1, m2, m3))
440 M = np.indices(self.s).transpose((1, 2, 3, 0)).reshape((-1, 3))
441 # Build index matrix N
442 N = M - (self.s / 2 < M) * self.s
443 return M, N
445 def _sample_unit_cell(self):
446 """Build the real-space sampling and all G-vector parameters."""
447 # Calculate index matrices
448 M, N = self._get_index_matrices()
449 # Build the real-space sampling
450 self._r = M @ inv(np.diag(self.s)) @ self.a
451 # Build G-vectors
452 self._G = 2 * np.pi * N @ inv(self.a.T)
453 # Calculate squared magnitudes of G-vectors
454 self._G2 = norm(self.G, axis=1) ** 2
455 # Calculate the G2 restriction
456 self._active = [
457 np.nonzero(2 * self.ecut >= norm(self.G + self.kpts.k[ik], axis=1) ** 2)
458 for ik in range(self.kpts.Nk)
459 ]
460 self._G2c = self.G2[np.nonzero(2 * self.ecut >= self._G2)]
461 # Calculate G+k-vectors
462 self._Gk2 = np.asarray(
463 [norm(self.G + self.kpts.k[ik], axis=1) ** 2 for ik in range(self.kpts.Nk)]
464 )
465 self._Gk2c = [self.Gk2[ik][self._active[ik]] for ik in range(self.kpts.Nk)]
466 # Calculate the structure factor per atom
467 self._Sf = np.exp(1j * self.G @ self.pos.T).T
469 # Create the grid used for the non-wave function fields and append it to the end
470 self._active.append(np.nonzero(2 * self.ecut >= self._G2))
471 self._Gk2 = np.vstack((self._Gk2, self._G2))
472 self._Gk2c.append(self._G2c)
474 O = operators.O
475 L = operators.L
476 Linv = operators.Linv
477 K = operators.K
478 T = operators.T
479 I = operators.I
480 J = operators.J
481 Idag = operators.Idag
482 Jdag = operators.Jdag
484 def __repr__(self):
485 """Print the parameters stored in the Atoms object."""
486 out = "Atom Valence Position"
487 for i in range(self.Natoms):
488 out += (
489 f"\n{self.atom[i]:>3} {self.Z[i]:>6} "
490 f"{self.pos[i, 0]:10.5f} {self.pos[i, 1]:10.5f} {self.pos[i, 2]:10.5f}"
491 )
492 return out