Fit Function: li_hex_schweinzer

Fit Function \[\sigma_{H^+}^{TX}\big(E\big) = 10^{-16}A_1 \Bigg\{ \frac{e^{-A_2/E}(A_{12} + \ln(A_{11}+A_3E))}{E}+ A_4\frac{e^{-A_5E}}{E^{A_6}} + A_7\frac{e^{-A_8E}}{1+A_9E^{A_{10}}}\Bigg\}\]
Comments Python code requires NumPy imported as `np`.

Python

Arguments
namedescriptionunitstype(s)
E impact energy keV u-1 float, np.ndarray
A1 fit coefficient cm2 keV-1 float
A2 fit coefficient keV float
A3 fit coefficient keV-1 float
A4 fit coefficient undef float
A5 fit coefficient keV-1 float
A6 fit coefficient float
A7 fit coefficient undef float
A8 fit coefficient keV-1 float
A9 fit coefficient undef float
A10 fit coefficient float
A11 fit coefficient float
A12 fit coefficient float
Return values
namedescriptionunitstype(s)
sigma cross section cm2 float, np.ndarray
Code 
def li_hex_schweinzer(E, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12):
    """
    This function calculates proton impact excitation cross sections (in cm2) of 
    Li.
    param E: requested proton-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)*(A12 + np.log(A11+ A3*E)))/E + 
                        A4*np.exp(-A5*E)/E**A6 + A7*np.exp(-A8/E)/(1+A9*E**A10))