ENERGY-DEPENDENCE OF THE STABILITY TYPE OF PERIODIC-ORBITS IN A SQUARE LATTICE

We report the first numerical results of stability versus energy for s hort-period orbits pertaining to two nonrelativistic Hamiltonian model s of channeling of charged particles in a square lattice. For both mod els, the orbits studied fall into two classes as regards the behavior of their Green's residue functions versus energy. The orbits in one of these classes exhibit nongeneric behavior near transition points of t he relevant Poincare maps and those in the other class are ordinary hy perbolic at all energies investigated.