def __setitem__(self, index, atom):
from collections import Sequence
from method.atom import Atom
from method import error
if isinstance(atom, Sequence):
for a in atom:
if not isinstance(a, Atom):
raise error.ValueError("Input should be of type Atom")
else:
if not isinstance(atom, Atom):
raise error.ValueError("Input should be of type Atom")
return self._atoms.__setitem__(index, atom)
def are_periodic_images(pos0, pos1, invcell=None, cell=None, tolerance=1e-8):
""" True if two vector are periodic images of one another
:param pos0:
First position
:param pos1:
Second position
:param invcell:
The *inverse* of the cell defining the periodicity
:param cell:
The cell defining the periodicity
:param tolerance:
Fuzzy tolerance criteria
Only one of cell and invcell need be given.
"""
from numpy import dot, floor
from numpy.linalg import inv, norm
from method import error
if invcell is None:
if cell is None:
raise error.ValueError("One of cell or invcell should be given")
invcell = inv(cell)
result = dot(invcell, pos0 - pos1)
result -= floor(result + tolerance)
return all(abs(result) < tolerance)
def poscar(path="POSCAR", types=None):
""" Tries to read a VASP POSCAR file.
:param path: Path to the POSCAR file. Can also be an object with
file-like behavior.
:type path: str or file object
:param types: Species in the POSCAR.
:type types: None or sequence of str
:return: `pylada.crystal.Structure` instance.
"""
import re
from os.path import join, exists, isdir
from copy import deepcopy
from numpy import array, dot, transpose
from numpy.linalg import det
from quantities import angstrom
from method.structure import Structure
from method import error
# if types is not none, converts to a list of strings.
if types is not None:
if isinstance(types, str):
types = [types] # can't see another way of doing this...
elif not hasattr(types, "__iter__"):
types = [str(types)] # single lone vasp.specie.Specie
else:
types = [str(s) for s in types]
if path is None:
path = "POSCAR"
if not hasattr(path, 'read'):
assert exists(path), IOError("Could not find path %s." % (path))
if isdir(path):
assert exists(join(path, "POSCAR")), IOError("Could not find POSCAR in %s." % (path))
path = join(path, "POSCAR")
result = Structure()
poscar = path if hasattr(path, "read") else open(path, 'r')
try:
# gets name of structure
result.name = poscar.readline().strip()
if len(result.name) > 0 and result.name[0] == "#":
result.name = result.name[1:].strip()
# reads scale
scale = float(poscar.readline().split()[0])
# gets cell vectors.
cell = []
for i in range(3):
line = poscar.readline()
assert len(line.split()) >= 3,\
RuntimeError("Could not read column vector from poscar: %s." % (line))
cell.append([float(f) for f in line.split()[:3]])
result.cell = transpose(array(cell))
vol = det(cell)
if scale < 1.E-8:
scale = abs(scale / vol) ** (1.0 / 3)
result.scale = scale * angstrom
# checks for vasp 5 input.
is_vasp_5 = True
line = poscar.readline().split()
for i in line:
if not re.match(r"[A-Z][a-z]?", i):
is_vasp_5 = False
break
if is_vasp_5:
text_types = deepcopy(line)
if types is not None and not set(text_types).issubset(set(types)):
raise error.ValueError("Unknown species in poscar: {0} not in {1}."
.format(text_types, types))
types = text_types
line = poscar.readline().split()
if types is None:
raise RuntimeError("No atomic species given in POSCAR or input.")
# checks/reads for number of each specie
if len(types) < len(line):
raise RuntimeError("Too many atomic species in POSCAR.")
nb_atoms = [int(u) for u in line]
# Check whether selective dynamics, cartesian, or direct.
first_char = poscar.readline().strip().lower()[0]
selective_dynamics = False
if first_char == 's':
selective_dynamics = True
first_char = poscar.readline().strip().lower()[0]
# Checks whether cartesian or direct.
is_direct = first_char not in ['c', 'k']
# reads atoms.
for n, specie in zip(nb_atoms, types):
for i in range(n):
line = poscar.readline().split()
pos = array([float(u) for u in line[:3]], dtype="float64")
if is_direct:
pos = dot(result.cell, pos)
result.add_atom(pos=pos, type=specie)
if selective_dynamics:
for which, freeze in zip(line[3:], ['x', 'y', 'z']):
if which.lower()[0] == 't':
result[-1].freeze = getattr(result[-1], 'freeze', '') + freeze
finally:
poscar.close()
return result