from __future__ import absolute_import, division, print_function
electron_radius = 2.818E-15 # classical electron radius in meters

plank_constant = 6.62606896E-34 # Joule-seconds

speed_of_light = 299792458.E0 # meters/second

Joules_per_eV = 1.602176487E-19

#conversion factor from inverse meters to eV:
eV_per_inv_meter = speed_of_light * plank_constant * 1./(Joules_per_eV)