"""Isotope data extracted from NIST public website.
Source data has been compiled by NIST:
https://www.nist.gov/pml/atomic-weights-and-isotopic-compositions-relative-atomic-masses
The atomic weights data were published in:
J. Meija et al, Atomic weights of the elements 2013,
Pure and Applied Chemistry 88, 265-291 (2016).
https://doi.org/10.1515/pac-2015-0305
http://www.ciaaw.org/atomic-weights.htm
Isotopic compositions data were published in:
Michael Berglund and Michael E. Wieser,
Isotopic compositions of the elements 2009 (IUPAC Technical Report)
Pure Appl. Chem., 2011, Vol. 83, No. 2, pp. 397-410
https://doi.org/10.1351/PAC-REP-10-06-02
The relative atomic masses of the isotopes data were published in:
M. Wang, G. Audi, A.H. Wapstra, F.G. Kondev, M. MacCormick, X. Xu,
and B. Pfeiffer, The AME2012 Atomic Mass Evaluation,
Chinese Phys. C 36 1603
https://doi.org/10.1088/1674-1137/36/12/003
http://amdc.impcas.ac.cn/evaluation/data2012/ame.html
"""
from urllib import request
[docs]def download_isotope_data():
"""Download isotope data from NIST public website.
Relative atomic masses of individual isotopes their abundance
(mole fraction) are compiled into a dictionary. Individual items can be
indexed by the atomic number and mass number, e.g. titanium-48:
>>> from ase.data.isotopes import download_isotope_data
>>> isotopes = download_isotope_data()
>>> isotopes[22][48]['mass']
47.94794198
>>> isotopes[22][48]['composition']
0.7372
"""
url = 'http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl' \
'?ele=&ascii=ascii&isotype=all'
with request.urlopen(url) as fd:
txt = fd.read()
raw_data = txt.decode().splitlines()
return parse_isotope_data(raw_data)
def parse_isotope_data(raw_data):
# In the list of raw data, a string containing only a series of underscores
# preceeds the data for each element. So by getting the indexes of these
# strings, we are recording where in the data each element starts
indexes = [idx for (idx, line) in enumerate(raw_data) if "_____" in line]
isotopes = {}
for idx1, idx2 in zip(indexes, indexes[1:]):
atomic_number = int(raw_data[idx1 + 1].split()[0])
isotopes[atomic_number] = dct = {}
for isotope_idx in range(idx1 + 1, idx2):
mass_number = int(raw_data[isotope_idx][8:12])
# drop uncertainty
mass = float(raw_data[isotope_idx][13:31].split('(')[0])
try:
composition = float(raw_data[isotope_idx][32:46].split('(')[0])
except ValueError:
composition = 0.0
dct[mass_number] = {'mass': mass, 'composition': composition}
return isotopes