CORNER TRANSFER-MATRIX OF AN ASYMMETRIC 6-VERTEX MODEL

We consider a free Fermion six-vertex model with asymmetrically chosen vertex weights from the point of view of its corner transfer matrix. The generator of the corner transfer matrix then corresponds to a quan tum XY spin chain Hamiltonian in an inhomogeneous magnetic field. The diagonalisation of the Hamiltonian employs orthogonal polynomials. The eigenenergy spectrum is related to the zeros of the asymptotic expans ion of these polynomials. Lastly we identify a critical region in the phase diagram of the model which is spanned by the magnetic field and the parameter describing the strength of the inhomogeneity.