1from ase.data import atomic_numbers, reference_states, chemical_symbols
2
3
4def get_element_info(symbol, latticeconstant):
5    if isinstance(symbol, str):
6        atomic_number = atomic_numbers[symbol]
7    else:
8        atomic_number = symbol
9        symbol = chemical_symbols[atomic_number]
10
11    if latticeconstant is None:
12        if reference_states[atomic_number]['symmetry'] in ['fcc', 'bcc', 'sc']:
13            lattice_constant = reference_states[atomic_number]['a']
14        else:
15            raise NotImplementedError(
16                ("Cannot guess lattice constant of a %s element." %
17                 (reference_states[atomic_number]['symmetry'],)))
18    else:
19        if isinstance(latticeconstant, (int, float)):
20            lattice_constant = latticeconstant
21        else:
22            raise ValueError("Lattice constant must be of type int or float.")
23
24    return symbol, atomic_number, lattice_constant
25