def alpha_B_HII(temperature):
    """
    Calculate the HII recombination rate
    This is the rate at which ionised hydrogen recombines 
      into neutral hydrogen
    Total recombinations per second per unit volume = alpha * ne * nH
    ne = electron number density
    nH = hydrogen number density

    Parameters
    ----------

    temperature: float
        Temperature in K

    Returns
    -------

    alpha_B_HII : float
        The recombination rate
    """
    # HII recombination rate
    # input  : T in K
    # output : HII recombination rate (in cm3 / s)
    l = 315614./temperature
    a = 2.753e-14 * l**1.5 / (1. + (l/2.74)**0.407)**2.242
    return a