Vol. 28, issue 12, article # 1

Abstract:

High order Rayleigh–Schrödinger perturbation theory and Pade–Hermite algebraic approximants are applied to calculate vibration energy levels of H₂O. Quadratic Katz branch points found by second-order algebraic approximants are used to classify resonances between vibrational states of the H₂O molecule. Apart from Fermi and Darling–Dennison resonances new resonance perturbations of states were found. Moreover, it was shown that all states with energy higher than 5000 cm^–1 are in one resonance polyad. This analysis helped us to improve polyad structure of vibrational states of water molecule.

Keywords:

perburbation theory, divergent series, algebraic approximants, vibrational energy levels, H2O molecule

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