Fit Function: li_hel_ns_schweinz

Fit Function \[\sigma_{H^+}^{TEL, \; Li(ns)}\big(E\big) = 10^{-16}A_1 \Bigg\{ \frac{e^{-A_2/E}\ln(1+A_3E)}{E}+ A_4\frac{e^{-A_5E}}{E^{A_6} + A_7E^{A_8}}\Bigg\}\]
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 float
Return values
namedescriptionunitstype(s)
sigma cross section cm2 float, np.ndarray
Code 
def li_hel_ns_schweinz(E, A1, A2, A3, A4, A5, A6, A7, A8):
    """
    This function calculates proton impact ionization cross sections (in cm2)
    from ns states 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)*np.log(1 + A3*E))/E 
                     + A4*np.exp(-A5*E)/(E**A6 + A7*E**A8))
    return sigma