Implementing Floquet BC with Linear Extrusion/Pointwise Constraint

Hi,

I am trying to implement the Floquet BC with Linear Extrusion/Pointwise Constraint as indicated in the thread :

http://www.comsol.com/community/forums/general/thread/5633/

I do not have access to the Floquet BC directly (as my lab has an older COMSOL version) and I have to go through the procedure with Linear Extrusion/Pointwise Constraint. I'm not sure if the procedure indicated in the thread works correctly.

I am trying to generate the band structure of a membrane and the eigen values are correct only at gamma, X and M points - at all other k-points, the eigenfrequencies are different (and also complex)

Is the procedure mentioned in that thread correct?

Thanks!