def lJ0(Tc, Vc):
    """
    Lennard Jones sigma and epsilon/k calculation:
        sigma = 0.841*Vc**(1/3)
        epsison/k = 0.75*Tc
    Parameters:
        Tc, critical temperature in K
    Returns:
        [sigma, epsilon/k]
    """
    return [0.841*Vc**(1/3),0.75*Tc]