  Quantum states of a discrete breather are studied in two ways. One method
involves numerical diagonalization of the Hamiltonian, the other uses the path
integral to examine correlations in the eigenstates. In both cases only the
central nonlinearity is retained. To reduce truncation effects in the numerical
diagonalization, a basis is used that involves a quadratic local mode. A
similar device is used in the path integral method for deducing localization.
Both approaches lead to the conclusion that aside from quantum tunneling the
quantized discrete breather is stable.
