Learning Forum

[anna.wirth-singh]

Hi Fatemeh,

It will be helpful if you can provide some more details about your simulation, perhaps a screenshot of the geometry or a plot of the Figure of Merit at each iteration. Other than the issues described, is the optimization proceeding as you would expect? Is the FOM progressing towards the desired outcome prior to freezing?

If you have modified the optimization structure, one possible explanation for these issues is that the geometry that is being optimized is extending outside the field monitor. While the structure may initially be contained within the field monitor region, it is possible that the updated structure is extending beyond the monitor region, and in this case the optimizer cannot calculate the shape derivatives. Additionally, the geometry should not exceed the mesh refinement region. A mesh refinement region should be placed over the region where the geometry may go to ensure that the mesh does not change during the optimization.

If you are using the setup script in the example, I recommend increasing the parameters size_x and/or size_y  to increase the size of the monitor and mesh override regions, and see if that resolves the issue.