def make_dynamical_potential_func(kBT_Gamma, density, SpringPotnlFunc):
    """
    Creates the function that calculates the potential given
    the position (in volts) and the radius of the particle. 

    Parameters
    ----------
    kBT_Gamma : float
        Value of kB*T/Gamma
    density : float
        density of the nanoparticle
    SpringPotnlFunc : function
        Function which takes the value of position (in volts)
        and returns the spring potential
    
    Returns
    -------
    PotentialFunc : function
        function that calculates the potential given
        the position (in volts) and the radius of the 
        particle.

    """
    def PotentialFunc(xdata, Radius):
        """
        calculates the potential given the position (in volts) 
        and the radius of the particle.

        Parameters
        ----------
        xdata : ndarray
            Positon data (in volts)
        Radius : float
            Radius in units of nm

        Returns
        -------
        Potential : ndarray
            Dynamical Spring Potential at positions given by xdata
        """
        mass = ((4/3)*pi*((Radius*10**-9)**3))*density
        yfit=(kBT_Gamma/mass)
        Y = yfit*SpringPotnlFunc(xdata)
        return Y
    return PotentialFunc