Semiclassical quantization of localized lattice solitons

From experiments on doped alkali-metal halide crystals there is reason to believe that localized, stationary lattice solitons, often called breathers, form and inhibit the crystal's relaxation. We quantize these excitations using the Einstein-Brillouin-Keller method (which is also generalized). Topologically independent loops on the Kolmogorov-Arnold-Moser torus are found stroboscopically, using easily calculated periods, and the classical action evaluated. Wave functions can also be evaluated using a path-integral-motivated semiclassical wave-function calculation.