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structure.py
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structure.py
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'''Program for generation of random crystal structures.
by Scott Fredericks, Spring 2018
Given a space group number between 1 and 230,
and a number N of atoms in the primitive cell,
produces a crystal structure with random atomic coordinates.
Outputs a cif file with conventional setting'''
import spglib
from vasp import read_vasp
from pymatgen.symmetry.groups import sg_symbol_from_int_number
from pymatgen.core.operations import SymmOp
from pymatgen.core.structure import Structure
from pymatgen.io.cif import CifWriter
from pymatgen.symmetry.analyzer import SpacegroupAnalyzer
from optparse import OptionParser
from scipy.spatial.distance import cdist
import numpy as np
from os.path import isfile
from random import uniform as rand
from random import choice as choose
from random import randint
from math import sqrt, pi, sin, cos, acos, fabs
import database.make_sitesym as make_sitesym
import database.hall as hall
from database.element import Element
from copy import deepcopy
#Define variables
#------------------------------
tol_m = 1.0 #seperation tolerance in Angstroms
max1 = 30 #Attempts for generating lattices
max2 = 30 #Attempts for a given lattice
max3 = 30 #Attempts for a given Wyckoff position
minvec = 2.0 #minimum vector length
ang_min = 30
ang_max = 150
#Define functions
#------------------------------
def create_matrix():
matrix = []
for i in [-1,0,1]:
for j in [-1,0,1]:
for k in [-1,0,1]:
matrix.append([i,j,k])
return np.array(matrix, dtype=float)
#Euclidean distance
def distance(xyz, lattice):
xyz = xyz - np.round(xyz)
matrix = create_matrix()
matrix += xyz
matrix = np.dot(matrix, lattice)
return np.min(cdist(matrix,[[0,0,0]]))
def check_distance(coord1, coord2, specie1, specie2, lattice):
"""
check the distances between two set of atoms
Args:
coord1: multiple list of atoms e.g. [[0,0,0],[1,1,1]]
specie1: the corresponding type of coord1, e.g. ['Na','Cl']
coord2: a list of new atoms: [0.5, 0.5 0.5]
specie2: the type of coord2: 'Cl'
lattice: cell matrix
"""
#add PBC
for i in [-1,0,1]:
for j in [-1,0,1]:
for k in [-1,0,1]:
np.append(coord2, coord2+[i,j,k])
coord2 = np.dot(coord2, lattice)
if len(coord1)>0:
for coord, element in zip(coord1, specie1):
coord = np.dot(coord, lattice)
d_min = np.min(cdist(coord, coord2))
tol = 0.5*(Element(element).covalent_radius + Element(specie2).covalent_radius)
#print(d_min, tol)
if d_min < tol:
return False
return True
else:
return True
def get_center(xyzs, lattice):
"""
to find the geometry center of the clusters under PBC
"""
matrix0 = create_matrix()
for atom1 in range(1,len(xyzs)):
dist_min = 10.0
for atom2 in range(0, atom1):
#shift atom1 to position close to atom2
#print(np.round(xyzs[atom1] - xyzs[atom2]))
xyzs[atom2] += np.round(xyzs[atom1] - xyzs[atom2])
#print(xyzs[atom1] - xyzs[atom2])
matrix = matrix0 + (xyzs[atom1] - xyzs[atom2])
matrix = np.dot(matrix, lattice)
dists = cdist(matrix, [[0,0,0]])
if np.min(dists) < dist_min:
dist_min = np.min(dists)
#print(dist_min, matrix[np.argmin(dists)]/4.72)
matrix_min = matrix0[np.argmin(dists)]
#print(atom1, xyzs[atom1], matrix_min, dist_min)
xyzs[atom1] += matrix_min
return xyzs.mean(0)
#generate random coordinate
def rand_coords(xyz_string):
"""
args:
xyz_string: 0, y, 1/4
return: random numbers for the places where x, y, z is present
"""
#xyz_string = ops[0].as_xyz_string()
xyz = []
x,y,z = np.random.random(3)
for content in xyz_string.strip('()').split(','):
if content.find('x')>=0:
xyz.append(x)
elif content.find('y')>=0:
xyz.append(y)
elif content.find('z')>=0:
xyz.append(z)
elif content.find('/')>=0:
tmp = content.split('/')
xyz.append(float(tmp[0])/float(tmp[1]))
else:
xyz.append(float(content))
return xyz
def para2matrix(cell_para):
""" 1x6 (a, b, c, alpha, beta, gamma) -> 3x3 representation -> """
matrix = np.zeros([3,3])
matrix[0][0] = cell_para[0]
matrix[1][0] = cell_para[1]*cos(cell_para[5])
matrix[1][1] = cell_para[1]*sin(cell_para[5])
matrix[2][0] = cell_para[2]*cos(cell_para[4])
matrix[2][1] = cell_para[2]*cos(cell_para[3])*sin(cell_para[4])
matrix[2][2] = sqrt(cell_para[2]**2 - matrix[2][0]**2 - matrix[2][1]**2)
return matrix
def matrix2para(matrix):
""" 3x3 representation -> 1x6 (a, b, c, alpha, beta, gamma)"""
cell_para = np.zeros(6)
cell_para[0] = np.linalg.norm(matrix[0])
cell_para[1] = np.linalg.norm(matrix[1])
cell_para[2] = np.linalg.norm(matrix[2])
cell_para[5] = angle(matrix[0], matrix[1])
cell_para[4] = angle(matrix[0], matrix[2])
cell_para[3] = angle(matrix[1], matrix[2])
return cell_para
def cellsize(sg):
"""
Returns the number of duplications in the conventional lattice
"""
symbol = sg_symbol_from_int_number(sg)
letter = symbol[0]
if letter == 'P':
return 1
if letter in ['A', 'C', 'I']:
return 2
elif letter in ['R']:
return 3
elif letter in ['F']:
return 4
else: return "Error: Could not determine lattice type"
def find_short_dist(coor, lattice, tol):
"""
here we find the atomic pairs with shortest distance
and then build the connectivity map
"""
pairs=[]
graph=[]
for i in range(len(coor)):
graph.append([])
for i1 in range(len(coor)-1):
for i2 in range(i1+1,len(coor)):
dist = distance(coor[i1]-coor[i2], lattice)
if dist <= tol:
#dists.append(dist)
pairs.append([i1,i2,dist])
pairs = np.array(pairs)
if len(pairs) > 0:
#print('--------', dists <= (min(dists) + 0.1))
d_min = min(pairs[:,-1]) + 1e-3
sequence = [pairs[:,-1] <= d_min]
#print(sequence)
pairs = pairs[sequence]
#print(pairs)
#print(len(coor))
for pair in pairs:
pair0=int(pair[0])
pair1=int(pair[1])
#print(pair0, pair1, len(graph))
graph[pair0].append(pair1)
graph[pair1].append(pair0)
return pairs, graph
def connected_components(graph): #Return a set of connected components for an undirected graph
"""
Given a graph (a 2d array of indices), return a set of
connected components, each connected component being an
(arbitrarily ordered) array of indices.
"""
def add_neighbors(el, seen=[]):
"""
Find all elements which are directly or indirectly
connected to el. Return an array (including el)
"""
#seen stores already-included indices
if seen == []: seen = [el]
#iterate through the neighbors (x) of el
for x in graph[el]:
if x not in seen:
seen.append(x)
#Recursively find neighbors of x
add_neighbors(x, seen)
return seen
def merge_coordinate(coor, lattice, wyckoff, tol):
while True:
pairs, graph = find_short_dist(coor, lattice, tol)
if len(pairs)>0:
if len(coor) > len(wyckoff[-1][0]):
merged = []
groups = connected_components(graph)
for group in groups:
#print(coor[group])
#print(coor[group].mean(0))
merged.append(get_center(coor[group], lattice))
merged = np.array(merged)
#print('Merging----------------')
coor = merged
else:#no way to merge
#print('no way to Merge, FFFFFFFFFFFFFFFFFFFFFFF----------------')
return coor, False
else:
return coor, True
def estimate_volume(numIons, species, factor=2.0):
volume = 0
for numIon, specie in zip(numIons, species):
volume += numIon*4/3*pi*Element(specie).covalent_radius**3
return factor*volume
def generate_lattice(sg, volume):
"""
generate the lattice according to the space group symmetry and number of atoms
if the space group has centering, we will transform to conventional cell setting
"""
minvec2 = minvec*minvec
alpha = np.radians(rand(ang_min, ang_max))
beta = np.radians(rand(ang_min, ang_max))
gamma = np.radians(rand(ang_min, ang_max))
#Triclinic
if sg <= 2:
x = sqrt(fabs(1. - cos(alpha)**2 - cos(beta)**2 - cos(gamma)**2 + 2.*cos(alpha)*cos(beta)*cos(gamma)))
volume = volume/x
a = rand(minvec, volume/minvec2)
b = rand(minvec, volume/(minvec*a))
c = volume/(a*b)
#Monoclinic
elif sg <= 15:
alpha, gamma = pi/2, pi/2
x = sin(beta)
volume = volume/x
a = rand(minvec, volume/(minvec2))
b = rand(minvec, volume/(minvec*a))
c = volume/(a*b)
#Orthorhombic
elif sg <= 74:
alpha, beta, gamma = pi/2, pi/2, pi/2
a = rand(minvec, volume/minvec2)
b = rand(minvec, volume/(minvec*a))
c = volume/(a*b)
#Tetragonal
elif sg <= 142:
alpha, beta, gamma = pi/2, pi/2, pi/2
c = rand(minvec, volume/minvec2)
a = sqrt(volume/c)
b = a
#Trigonal/Rhombohedral/Hexagonal
elif sg <= 194:
alpha, beta, gamma = pi/2, pi/2, pi/3*2
x = sqrt(3.)/2.
volume = volume/x
c = rand(minvec, volume/minvec2)
a = sqrt(volume/c)
b = a
#Cubic
else:
alpha, beta, gamma = pi/2, pi/2, pi/2
s = (volume) ** (1./3.)
a, b, c = s, s, s
return np.array([a, b, c, alpha, beta, gamma])
def check_compatible(numIons, wyckoff):
"""
check if the number of atoms is compatible with the wyckoff positions
needs to improve later
"""
N_site = [len(x[0]) for x in wyckoff]
for numIon in numIons:
if numIon % N_site[-1] > 0:
return False
return True
def filter_site(v): #needs to explain
w = v
for i in range(len(w)):
while w[i]<0: w[i] += 1
while w[i]>=1: w[i] -= 1
return w
def choose_wyckoff(wyckoffs, number):
"""
choose the wyckoff sites based on the current number of atoms
rules
1, the newly added sites is equal/less than the required number.
2, prefer the sites with large multiplicity
"""
for wyckoff in wyckoffs:
if len(wyckoff[0]) <= number:
return choose(wyckoff)
return False
def get_wyckoff_positions(sg):
"""find the wyckoff positions
Args:
sg: space group number (19)
Return: a list containg the operation matrix sorted by multiplicity
4a
[Rot:
[[ 1. 0. 0.]
[ 0. 1. 0.]
[ 0. 0. 1.]]
tau
[ 0. 0. 0.],
Rot:
[[-1. 0. 0.]
[ 0. -1. 0.]
[ 0. 0. 1.]]
tau
[ 0.5 0. 0.5],
Rot:
[[-1. 0. 0.]
[ 0. 1. 0.]
[ 0. 0. -1.]]
tau
[ 0. 0.5 0.5],
Rot:
[[ 1. 0. 0.]
[ 0. -1. 0.]
[ 0. 0. -1.]]
tau
[ 0.5 0.5 0. ]]]
"""
array = []
hall_number = hall.hall_from_hm(sg)
wyckoff_positions = make_sitesym.get_wyckoff_position_operators('database/Wyckoff.csv', hall_number)
for x in wyckoff_positions:
temp = []
for y in x:
temp.append(SymmOp.from_rotation_and_translation(list(y[0]), filter_site(y[1]/24)))
array.append(temp)
i = 0
wyckoffs_organized = [[]] #2D Array of Wyckoff positions organized by multiplicity
old = len(array[0])
for x in array:
mult = len(x)
if mult != old:
wyckoffs_organized.append([])
i += 1
old = mult
wyckoffs_organized[i].append(x)
return wyckoffs_organized
def generate_crystal(sg, species, numIons, factor):
numIons *= cellsize(sg)
volume = estimate_volume(numIons, species, factor)
wyckoffs = get_wyckoff_positions(sg) #2D Array of Wyckoff positions organized by multiplicity
Msg1 = 'Error: the number is incompatible with the wyckoff sites choice'
Msg2 = 'Error: failed in the cycle of generating structures'
Msg3 = 'Warning: failed in the cycle of adding species'
Msg4 = 'Warning: failed in the cycle of choosing wyckoff sites'
Msg5 = 'Finishing: added the specie'
Msg6 = 'Finishing: added the whole structure'
if check_compatible(numIons, wyckoffs) is False:
print(Msg1)
else:
for cycle1 in range(max1):
#1, Generate a lattice
cell_para = generate_lattice(sg, volume)
cell_matrix = para2matrix(cell_para)
coordinates_total = [] #to store the added coordinates
sites_total = [] #to store the corresponding specie
good_structure = False
for cycle2 in range(max2):
coordinates_tmp = deepcopy(coordinates_total)
sites_tmp = deepcopy(sites_total)
#Add specie by specie
for numIon, specie in zip(numIons, species):
numIon_added = 0
tol = max(0.5*Element(specie).covalent_radius, tol_m)
#Now we start to add the specie to the wyckoff position
#print(wyckoffs[-1][0][0].as_xyz_string)
for cycle3 in range(max3):
#Choose a random Wyckoff position for given multiplicity: 2a, 2b, 2c
ops = choose_wyckoff(wyckoffs, numIon-numIon_added)
if ops is not False:
#Generate a list of coords from ops
#point = rand_coords() #ops[0].as_xyz_string())
point = np.random.random(3)
#print('generating new points:', point)
coords = np.array([op.operate(point) for op in ops])
#merge_coordinate if the atoms are close
coords_toadd, good_merge = merge_coordinate(coords, cell_matrix, wyckoffs, tol)
if good_merge:
coords_toadd -= np.floor(coords_toadd) #scale the coordinates to [0,1], very important!
#print('existing: ', coordinates_tmp)
if check_distance(coordinates_tmp, coords_toadd, sites_tmp, specie, cell_matrix):
coordinates_tmp.append(coords_toadd)
sites_tmp.append(specie)
numIon_added += len(coords_toadd)
if numIon_added == numIon:
#print(Msg5)
coordinates_total = deepcopy(coordinates_tmp)
sites_total = deepcopy(sites_tmp)
break
if numIon_added == numIon:
print(Msg6)
good_structure = True
break
elif cycle2+1 == max2:
#print(coordinates_total)
print(Msg3)
if good_structure:
final_coor = []
final_site = []
final_lattice = cell_matrix
for coor, ele in zip(coordinates_total, sites_total):
for x in coor:
final_coor.append(x)
final_site.append(ele)
if len(final_coor) > 48:
return Structure(final_lattice, final_site, np.array(final_coor)), False
return Structure(final_lattice, final_site, np.array(final_coor)), True
return Msg2, False
if __name__ == "__main__":
#-------------------------------- Options -------------------------
parser = OptionParser()
parser.add_option("-s", "--spacegroup", dest="sg", metavar='sg', default=206, type=int,
help="desired space group number: 1-230, e.g., 206")
parser.add_option("-e", "--element", dest="element", default='Li',
help="desired elements: e.g., Li", metavar="element")
parser.add_option("-n", "--numIons", dest="numIons", default=16,
help="desired numbers of atoms: 16", metavar="numIons")
parser.add_option("-v", "--volume", dest="factor", default=2.0, type=float,
help="volume factors: default 2.0", metavar="factor")
(options, args) = parser.parse_args()
element = options.element
number = options.numIons
numIons = []
if element.find(',') > 0:
system = element.split(',')
for x in number.split(','):
numIons.append(int(x))
else:
system = [element]
numIons = [int(number)]
for i in range(100):
numIons0 = np.array(numIons)
sg = randint(2,230)
#new_struct, good_struc = generate_crystal(options.sg, system, numIons0, options.factor)
new_struct, good_struc = generate_crystal(sg, system, numIons0, options.factor)
if good_struc:
new_struct.to(fmt="poscar", filename = '1.vasp')
cell = read_vasp('1.vasp')
#ans = spglib.get_spacegroup(cell)
ans = spglib.get_symmetry_dataset(cell, symprec=1e-1)['number']
print('Space group requested: ', sg, 'generated', ans)
if ans < int(sg/1.2):
print('something is wrong')
break
#print(CifWriter(new_struct, symprec=0.1).__str__())
#print('Space group:', finder.get_space_group_symbol(), 'tolerance:', tol)
#output wyckoff sites only
else:
print('something is wrong')
#print(len(new_struct.frac_coords))
break
#print(new_struct)