Neumann boundary condition not allowed with skew unit cell

[ruyam]

I have a structure with Gate on Top. As I used Neumann Boundary Condition in the direction of Gate and run the script I get the following error? Why is it this the case? 

NLValueError: Neumann boundary conditions are not allowed with skew unit cells.

We have to use Neumann boundary condition for gated device, right?

[Anders Blom]

The error message tells you what is wrong. It's always best to work with orthogonal cells if you are using gates and dielectrica. It's not strictly necessary, but almost.