Fit Function: h_hex_janev_12

Fit Function \[\sigma_{ex}^{1\rightarrow 2}(E)=10^{-16}A_1 \Bigg[\frac{e^{-\frac{A_2}{E}}\ln(1+A_3E)}{E} + \frac{A_4e^{-A_5E}}{E^{A_6}} + \frac{A_7e^{-\frac{A_8}{E}}}{1+A_9E^{A_{10}}}\Bigg]\]
Comments Python code requires NumPy imported as `np`.

Python

Arguments
namedescriptionunitstype(s)
E impact energy keV u-1 float, np.ndarray
A1 fit coefficient keV cm2 u-1 float
A2 fit coefficient keV u-1 float
A3 fit coefficient keV-1 u float
A4 fit coefficient undef float
A5 fit coefficient keV-1 u float
A6 fit coefficient float
A7 fit coefficient undef float
A8 fit coefficient keV u-1 float
A9 fit coefficient undef float
A10 fit coefficient float
Return values
namedescriptionunitstype(s)
sigma cross section cm2 float, np.ndarray
Code 
def h_hex_janev_12(E, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10):
    """
    This function calculates proton impact excitation cross sections (in cm2) of 
    H n=1 to n=2 and He+2 impact excitation of H n=1 to n=2,3,4.
    param E: requested impact energy in keV/u
    type E: float, np.ndarray
    param Ai: fit coefficient 
    type Ai: float
    """
    sigma = 1e-16 * A1 * (np.exp(-A2/E) * np.log(1 + A3*E) / E + A4*np.exp(-A5*E)/E**A6 + 
                           A7*np.exp(-A8/E)/(1+A9*E**A10))
    return sigma