Fit Function: li_ein_lotz

Fit Function \[\begin{align*} \sigma_{e}^{ion}\big(E\big) = 10^{-14} \Bigg(\frac{4}{EI} \ln\bigg(\frac{E}{I}\bigg)\Bigg[1-0.7 exp\bigg(\frac{-2.4(E-I)}{I} \bigg) \Bigg] \\ + \frac{8.2}{58E} \ln\bigg(\frac{E}{58}\bigg)\Bigg[1-0.6 exp\bigg(\frac{-0.6(E-58)}{58} \bigg) \Bigg]\Bigg) \end{align*}\]
Comments Python code requires NumPy imported as `np`.

Python

Arguments
namedescriptionunitstype(s)
E impact energy eV float, np.ndarray
I ionization energy eV float
Return values
namedescriptionunitstype(s)
sigma cross section cm2 float, np.ndarray
Code 
def li_ein_lotz(E, I):
    """
    This function calculates electron impact ionization cross sections (in cm2) of 
    Li 4s to 4f.
    param E: requested electron-impact energy in eV
    type E: float, np.ndarray
    param I: ionization energy in eV
    type I: float
    """
    sigma = 1e-14* ((1*4*np.log(E/I)/(E*I))*(1-0.7*np.exp(-2.4*(E/I -1))) + 
                       (2*4.2*np.log(E/58)/(E*58))*(1-0.6*np.exp(-0.6*(E/58 -1))))
    return sigma