Fit Function: SPTAEX

Fit Function \[Y(E_0, \alpha) = Y(E_0, 0)\left\{\cos\left[\left( \frac{\alpha}{\alpha_0}\frac{\pi}{2} \right)^c\right]\right\}^{-f} \exp\left\{b\left(1-\frac{1}{\cos\left[\left( \frac{\alpha}{\alpha_0}\frac{\pi}{2} \right)^c\right]}\right)\right\}\]
Comments Extended Yamamura formula

Python

Arguments
namedescriptionunitstype(s)
alpha projectile impact angle measure from normal to the surface deg float, np.ndarray
f fit coefficient float
b fit coefficient float
c fit coefficient float
Y0 fit coefficient: Y(E0, 0), the sputtering yield at E0, normal incidence float
alpha0 fit coefficient rad float
Return values
namedescriptionunitstype(s)
Y(E0, alpha) sputtering yield float, np.ndarray
Code 
def sptaex(alpha, f, b, c, Y0, alpha0):
    alpha = np.radians(alpha)
    aratio = alpha * pio2 / alpha0
    cs = np.cos(aratio ** c)
    xs1 = np.exp(b * (1 - 1 / cs))
    xs2 = 1 / cs**f
    Y = Y0 * xs1 * xs2
    return np.clip(Y, 0, None)