Diverging fields encountered when using periodic boundary condition

Hello to all,

I am well aware of this problem of diverging fields through forum discussions. But this is a different problem that I am facing.

To study E field enhancements, I am trying to simulate a structure of which I am doing periodic variation analysis, lets say for 5 values of periods, i.e., P = 500, 550, 600, 650 and 700. I am using periodic boundary condition. For the first 3 cases, the simulations ran without any problem. However, for P = 650 and 700, The autoshuttoff kept on increasing and finally gave this error. I tried different solutions given on the forum. Also, I tried using stabilized PML option, using which the error was gone, but when I visualized the E field, it gave an unexpected profile of the E field curve.
I should mention here that I have checked the courant stability condition and it was met. So what is it that is causing such abnormal behaviour.

Please somebody help.

Thanks a lot.

Hi @eez168085

Diverging problem can occur for many different reason, as you mentioned. I think the easiest and fastest way to solve the problem is to upload your simulation file for a review.