def squareCC(size):
    """
    Return the average clustering coefficient of a cubic droplet of a certain 
    size, when the square diagonals link the junctions.

    Parameters:
    -----------
    size: integer
        The size of the side of the cube.

    Returns:
    --------
    CC/size**3: float
        The average clustering coefficient of the dataframe.
    """
    vertice = 4/5
    edge = 7/12
    facet = 6/13
    core = 20/51
    
    CC = 8*vertice + 12*(size-2)*edge + 6*(size-2)**2*facet + (size-2)**3*core
    return CC/size**3