SEARCH Articles Figures Tables Anharmonic coupling theory Anharmonic coupling theory Fermi resonance Anharmonic coupling theory Hamiltonian modes Anharmonic coupling theory adiabatic approximation Anharmonic coupling theory effect Anharmonic coupling theory parameters Anharmonic coupling theory systems Anharmonic oscillator-molecular orbital theory connection Anharmonicity Anharmonicity perturbation theory Anharmonicity, spectroscopic perturbation theory Perturbation theory anharmonic oscillator Perturbation theory anharmonic vibrational spectroscop Strong anharmonic coupling theory Strong coupling theory, anharmonicity Strong coupling theory, anharmonicity hydrogen bonds