Fit Function: h_hcx_janev_scaled

Fit Function \[\sigma_{CX}^{n>1}(E)= \frac{A_7^410^{-16}A_1 \ln \big( \frac{A_2}{\tilde E} + A_6 \big)}{1 + A_3 \tilde E + \big( A_4 \tilde E \big)^{3.5} + \big(A_5 \tilde E \big)^{5.4} }, \tilde E = EA_7^2\]
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 float
A2 fit coefficient keV u-1 float
A3 fit coefficient keV-1 u float
A4 fit coefficient keV-1 u float
A5 fit coefficient keV-1 u float
A6 fit coefficient float
A7 main quantum number float
Return values
namedescriptionunitstype(s)
sigma cross section cm2 float, np.ndarray
Code 
def h_hcx_janev_scaled(E, A1, A2, A3, A4, A5, A6, A7):
    """
    This function calculates proton impact charge exchange cross sections (in cm2) of 
    H n>1.
    param E: requested electron-impact energy in keV
    type E: float, np.ndarray
    param Ai: fit coefficient 
    type Ai: float
    """
    e = E*A7**2
    sigma = A7**4 * 1e-16 * A1 * np.log(A2/e + A6) / 
    (1 + A3*e +(A4*e)**3.5 + (A5*e)**5.4)
    return sigma