"""This module contains functions to read from QBox output files"""
import re
import xml.etree.ElementTree as ET
from ase import Atom, Atoms
from ase.calculators.singlepoint import SinglePointCalculator
from ase.utils import reader
# Compile regexs for fixing XML
re_find_bad_xml = re.compile(r'<(/?)([A-z]+) expectation ([a-z]+)')
[docs]
@reader
def read_qbox(f, index=-1):
"""Read data from QBox output file
Inputs:
f - str or fileobj, path to file or file object to read from
index - int or slice, which frames to return
Returns:
list of Atoms or atoms, requested frame(s)
"""
# Check whether this is a QB@all output
version = None
for line in f:
if '<release>' in line:
version = ET.fromstring(line)
break
if version is None:
raise Exception('Parse Error: Version not found')
is_qball = 'qb@LL' in version.text or 'qball' in version.text
# Load in atomic species
species = {}
if is_qball:
# Read all of the lines between release and the first call to `run`
species_data = []
for line in f:
if '<run' in line:
break
species_data.append(line)
species_data = '\n'.join(species_data)
# Read out the species information with regular expressions
symbols = re.findall('symbol_ = ([A-Z][a-z]?)', species_data)
masses = re.findall('mass_ = ([0-9.]+)', species_data)
names = re.findall('name_ = ([a-z]+)', species_data)
numbers = re.findall('atomic_number_ = ([0-9]+)', species_data)
# Compile them into a dictionary
for name, symbol, mass, number in zip(names, symbols, masses, numbers):
spec_data = dict(
symbol=symbol,
mass=float(mass),
number=float(number)
)
species[name] = spec_data
else:
# Find all species
species_blocks = _find_blocks(f, 'species', '<cmd>run')
for spec in species_blocks:
name = spec.get('name')
spec_data = dict(
symbol=spec.find('symbol').text,
mass=float(spec.find('mass').text),
number=int(spec.find('atomic_number').text))
species[name] = spec_data
# Find all of the frames
frames = _find_blocks(f, 'iteration', None)
# If index is an int, return one frame
if isinstance(index, int):
return _parse_frame(frames[index], species)
else:
return [_parse_frame(frame, species) for frame in frames[index]]
def _find_blocks(fp, tag, stopwords='[qbox]'):
"""Find and parse a certain block of the file.
Reads a file sequentially and stops when it either encounters the
end of the file, or until the it encounters a line that contains a
user-defined string *after it has already found at least one
desired block*. Use the stopwords ``[qbox]`` to read until the next
command is issued.
Groups the text between the first line that contains <tag> and the
next line that contains </tag>, inclusively. The function then
parses the XML and returns the Element object.
Inputs:
fp - file-like object, file to be read from
tag - str, tag to search for (e.g., 'iteration').
`None` if you want to read until the end of the file
stopwords - str, halt parsing if a line containing this string
is encountered
Returns:
list of xml.ElementTree, parsed XML blocks found by this class
"""
start_tag = f'<{tag}'
end_tag = f'</{tag}>'
blocks = [] # Stores all blocks
cur_block = [] # Block being filled
in_block = False # Whether we are currently parsing
for line in fp:
# Check if the block has started
if start_tag in line:
if in_block:
raise Exception('Parsing failed: Encountered nested block')
else:
in_block = True
# Add data to block
if in_block:
cur_block.append(line)
# Check for stopping conditions
if stopwords is not None:
if stopwords in line and len(blocks) > 0:
break
if end_tag in line:
if in_block:
blocks.append(cur_block)
cur_block = []
in_block = False
else:
raise Exception('Parsing failed: End tag found before start '
'tag')
# Join strings in a block into a single string
blocks = [''.join(b) for b in blocks]
# Ensure XML compatibility. There are two specific tags in QBall that are
# not valid XML, so we need to run a
blocks = [re_find_bad_xml.sub(r'<\1\2_expectation_\3', b) for b in blocks]
# Parse the blocks
return [ET.fromstring(b) for b in blocks]
def _parse_frame(tree, species):
"""Parse a certain frame from QBOX output
Inputs:
tree - ElementTree, <iteration> block from output file
species - dict, data about species. Key is name of atom type,
value is data about that type
Return:
Atoms object describing this iteration"""
# Load in data about the system
energy = float(tree.find("etotal").text)
# Load in data about the cell
unitcell = tree.find('atomset').find('unit_cell')
cell = []
for d in ['a', 'b', 'c']:
cell.append([float(x) for x in unitcell.get(d).split()])
stress_tree = tree.find('stress_tensor')
if stress_tree is None:
stresses = None
else:
stresses = [float(stress_tree.find(f'sigma_{x}').text)
for x in ['xx', 'yy', 'zz', 'yz', 'xz', 'xy']]
# Create the Atoms object
atoms = Atoms(pbc=True, cell=cell)
# Load in the atom information
forces = []
for atom in tree.find('atomset').findall('atom'):
# Load data about the atom type
spec = atom.get('species')
symbol = species[spec]['symbol']
mass = species[spec]['mass']
# Get data about position / velocity / force
pos = [float(x) for x in atom.find('position').text.split()]
force = [float(x) for x in atom.find('force').text.split()]
momentum = [float(x) * mass
for x in atom.find('velocity').text.split()]
# Create the objects
atom = Atom(symbol=symbol, mass=mass, position=pos, momentum=momentum)
atoms += atom
forces.append(force)
# Create the calculator object that holds energy/forces
calc = SinglePointCalculator(atoms,
energy=energy, forces=forces, stress=stresses)
atoms.calc = calc
return atoms