MOMENTS OF ENERGY-LEVEL DISTRIBUTIONS IN VIBRATIONAL-SPECTRA

Expressions for moments of the spectral density distribution of a syst em described by a non-symmetric N-particle Hamiltonian are derived. In particular, this kind of Hamiltonian may represent N coupled oscillat ors; then its spectrum models the vibrational spectrum of a molecule. It is assumed that the Hamiltonian is defined in a finite-dimensional space formed by products of orthogonal eigenstates of some one-body Ha miltonians. Possible applications of the formalism are briefly discuss ed.