Difficulties and errors when trying to apply Robin Boundary Conditions with data from another domain (Eigenvalue Problem)

variational formulation
6

After your insight, I found the solution, using uu2.dx(0) + uu2.dx(1) instead of grad(uu2).

## Schwarz Alternating Algorithm
# First Step: Do F1 = du2/dn2 G1 = u2
V1 = FunctionSpace(omega1,"Lagrange", 1)
V2 = FunctionSpace(omega2, "Lagrange",1)

g1 = Function(V1)
LagrangeInterpolator.interpolate(uu2,g1)
f1 = Function(V1)

ff2 = project(uu2.dx(0) +uu2.dx(1),V2)
LagrangeInterpolator.interpolate(ff2,f1)

Now works! Thanks!