def METHOD_NAME(self, T, M, mu):
    """
    Return the value of the Lennard-Jones collision frequency in Hz at the
    given temperature `T` in K for colliders with the given concentration
    `M` in mol/m^3 and reduced mass `mu` in amu.
    This seems to also exist in rmgpy.pdep.configuration.calculate_collision_frequency
    Why the redundancy?
    """
    sigma = self.sigma.value_si
    epsilon = self.epsilon.value_si
    M *= constants.Na  # mol/m^3 -> molecules/m^3
    Tred = constants.R * T / epsilon
    omega22 = 1.16145 * Tred ** (-0.14874) + 0.52487 * np.exp(-0.77320 * Tred) + 2.16178 * np.exp(-2.43787 * Tred)
    mu *= constants.amu
    return omega22 * np.sqrt(8 * constants.kB * T / constants.pi / mu) * constants.pi * sigma * sigma * M