Download atomic form factors from henke and NIST directly within python

atomicformfactor.py

import functools
import requests
from io import StringIO
from bs4 import BeautifulSoup
from urllib.parse import urljoin

# Henke

def atomicformfactor_henke(element):
    element = element.lower()
    return _download_henke(element)

@functools.cache
def _atomicformfactor_henke(element):
    urltmplate = 'https://henke.lbl.gov/optical_constants/sf/{element}.nff'
    url = urltmplate.format(element=element)
    r = requests.get(url)
    data = np.genfromtxt(StringIO(r.text))[1:]
    f = data[:,1] + 1j*data[:,2]
    eV = data[:,0]
    return eV, f


# NIST

@functools.cache
def atomicformfactor_nist(Z):
    #baseurl = 'https://physics.nist.gov/cgi-bin'
    urltmplate = 'https://physics.nist.gov/cgi-bin/ffast/ffast.pl?gtype=4&Z={Z}'
    url = urltmplate.format(Z=Z)
    session = requests.Session()
    r = session.get(url).content
    # parse page
    soup = BeautifulSoup(r)
    tabledata = soup.select('body > pre')[0].text.splitlines()[3:]
    tabledata = '\n'.join(tabledata)
    data = np.genfromtxt(StringIO(tabledata))
    eV = data[:, 0] * 1e3
    f = data[:,1] + 1j*data[:,2]
    return eV, f