[[Image:FDTD57.png|thumb|390px|EM.Tempo's Run dialog.]]
[[Image:FDTD58.png|thumb|600px|EM.Tempo's Simulation Engine Settings dialog.]]
[[Image:FDTD66.png|thumb|480px|EM.Tempo's output window.]]
Once you build your physical structure in the project workspace and define an excitation source, you are ready to run an FDTD simulation. The simulation engine will run even if you have not defined any observables. Obviously, no simulation data will be generated in that case. EM.Tempo currently offers several different simulation modes as follows:
For structures excited with a plane wave source, there are two standard FDTD formulations: '''Scattered Field '''(SF) formulation and '''Total Field - Scattered Field''' (TF-SF) formulation. [[EM.Tempo]] offers both formulations. The TF-SF solver is the default choice and is typically much faster than the SF solver for most problems. In two cases, when the structure has periodic boundary conditions or infinite CPML boundary conditions (zero domain offsets), only the SF solver is available.
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[[Image:FDTD58.png|thumb|left|600px|EM.Tempo's simulation engine settings dialog.]]
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== Working with FDTD Simulation Data ==