Multiquanta breather model for PtCl - art. no. 020301

We study the many-quanta problem of an intramolecular vibrational excitatio n interacting with optical phonons, that may represent the nonlinearity fro m intrinsic electron-lattice interactions. In the adiabatic limit we calcul ate numerically the ground-state energy and the corresponding wave function s for N vibrational quanta. In the one-dimensional case we find strong reds hifts in the overtone spectra and an increasing spatial localization as the number of quanta increases. Through model parameter fitting we achieve ver y good quantitative agreement with experimental resonant Raman scattering m easurements in the quasi-one-dimensional charge transfer solid PtCl. Accura te analytical expressions for the redshifts are also obtained.