There are two macros which allow the capacitance matrix calculus, one for 2D and the other for 3D models. Their paths are:
Once the capacitance matrix is obtained the equivalent electric scheme between capacitive regions RC_1 and RC_2 is shown in the figure bellow, where C_11, C_12 and C_22 are the (1,1), (1,2) and (2,2) elements of the capacitance matrix, respectively.