Vibrational-Rotational Excitations in Nonlinear Molecular Systems

Abstract

1 Introduction.- 2 Classical theory of nonlinear vibrational systems local modes.- 2.1 Survey of classical mechanics introduction to local modes.- 2.2 Method of averaging.- 2.3 Two weakly coupled Morse oscillators: dynamics and local - mode formation.- 2.4 Analysis of phase trajectories with the help of Poincare sections, numerical results.- 3 Coupled nonlinear oscillators: formation and decay of local modes.- 3.1 Two weakly coupled nonlinear oscillators: decay of normal modes.- 3.2 Multi-oscillator systems: local modes' and normal modes' representations.- 3.3 Morse oscillators: calculation of resonance linewidths and criteria for the appearance of local modes.- 3.4 Coupled nonlinear oscillators: localized vibrational excitations and their asymptotic stability.- 3.5 Canonical transformation to local - mode representation.- 4 Discrete breathers.- 4.1 Breathers in Hamiltonian lattices.- 4.2 Discrete breathers in one-dimensional chains.- 4.3 Arguments for the existence of discrete breathers: some mathematics.- 4.4 Discrete breathers: numerical experiments.- 4.5 Discrete breathers in lattices with a homogeneous potential.- 4.6 An exactly solvable Hamiltonian lattice.- 5 Quantum theory of vibrational - rotational spectra in XY2 - type molecules.- 5.1 Quantum theory of two Morse oscillators: stretching - vibration spectra in XY2 molecules.- 5.2 Stretching - vibration spectra: nonresonant modes' effect upon clusterization of levels.- 5.3 Spectrum of stretching vibrations in XY2 molecules: numerical studies.- 6 Quantum Hamiltonians of vibrational - rotational excitations in polyatomic molecules method of contact transformations.- 6.1 Quantum Hamiltonian of polyatomic molecules.- 6.2 Molecular Hamiltonian in the inner basis representation 'coordinates - angles'.- 6.3 Contact transformation.- 6.4 Vibrational-rotational Hamiltonian for XY2 molecule in the inner basis representation 'coordinates - angles'.- 7 Semiclassical rotational spectra of rigid and semi-rigid molecules clusterization of levels and internal symmetry.- 7.1 Spectrum of polyatomic molecules: clusterization of rotational levels.- 7.2 Rotational spectrum of rigid and semi-rigid molecules: semi-classical approach.- 7.3 Symmetry - based analysis of rotational clusters.- 7.4 Tunnelling matrix.- 7.5 Violation of permutation symmetry and the super-hyperfine structure.- 8 Interaction of vibrations and rotations polyads and their spectra.- 8.1 Interaction of local vibration modes and rotation in hydrides.- 8.2 Rotational - vibrational spectrum in the vicinity of bifurcation points.- 8.3 Spectral properties of systems with Fermi resonances.- 9 Intramolecular relaxation of vibrations in the presence of local modes.- 9.1 Localized long - living vibrational states in molecular crystals.- 9.2 Population inversion of localized long - living vibrational states in a cold lattice.- 9.3 Interaction of isolated levels with the continuous spectrum.- 10 IR spectra and intramolecular relaxation.- 10.1 Redistribution of intramolecular energy: influence of multi-mode resonance.- 10.2 Relation between the absorption linewidths, intramolecular vibrations evolution, and unimolecular decay rates.- 10.3 Effect of anharmonicity on IR spectra of polyatomic molecules.- 10.4 Correlation between structure and IR spectra in polyatomic molecules.- 11 Conclusion.