In the finite difference method, the computational domain is discretized using a 3D rectangular grid. The grid spacing along the three principal coordinate axes is denoted by Δx, Δy and Δz, respectively. The potential at any point (x,y,z) in the space can be expressed in terms of the potentials at six neighboring grid points along the principal axes. The creates a 7-point computational molecule shown in the figure below:
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[[Image:FD 7Point.png|thumb|left|480px| The 7-point computational molecule used by the finite difference solver.]]
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== 2D Quasi-Static Solution of TEM Transmission Line Structures ==