Hi,
You first say you consider the Helmholtz equation in the time domain (with a time derivative), but then write an eigenvalue equation. If you want eigenvalues/eigenvectors you should indeed call the EigenValue() function. In your script you solve a problem without a source that has a solution Emag=0.
Please refer to the tutorial example for acoustics: Acoustics. It is for a Neumann boundary condition, but just add your on() condition to varf op().
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