  A topological phase can often be represented by a corresponding wavefunction
(exact eigenstate of a model Hamiltonian) that has a higher underlying symmetry
than necessary. When the symmetry is explicitly broken in the Hamiltonian, the
model wavefunction fails to account for the change due to the lack of a
variational parameter. Here we exemplify the case by an integer quantum Hall
system with anisotropic interaction. We demonstrate the recovery of the
variational parameter in a single-mode approximation, which is consistent with
the recently proposed geometric consideration of the quantum Hall phases.
