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Theoretical infrared line shapes of H‐bonds within the strong anharmonic coupling theory and Fermi resonances effects
Author(s) -
Issaoui Noureddine,
Rekik Najeh,
Oujia Brahim,
Wójcik Marek J.
Publication year - 2010
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22395
Subject(s) - anharmonicity , fermi resonance , physics , fermi gamma ray space telescope , dipole , coupling (piping) , atomic physics , condensed matter physics , quantum mechanics , molecular physics , chemistry , infrared , materials science , metallurgy
Abstract In this article, we extend a previous work toward presenting a theoretical study of the effects of Fermi resonances and the fundamental anharmonic coupling parameter α between the high‐frequency mode and the H‐bond bridge. The model incorporates (i) both intrinsic anharmonicities of the fast mode (double well potential) and the H‐bond Bridge (Morse potential), (ii) strong anharmonic coupling theory, (iii) Fermi resonances by the aid of an anharmonic coupling between the fast mode and one or several harmonic bending modes, (iv) quadratic modulation of both the angular frequency and the equilibrium position of the X $\vec H$ …Y stretching mode on the intermonomer $\vec X$ H… $\vec Y$ motions, and (v) the quantum direct (fast and bending modes) and indirect dampings (slow mode). The IR spectral density is obtained by Fourier transform of the autocorrelation function of the transition dipole moment operator of the X H bond. The numerical calculation shows that Fermi resonances generate very complicated profiles with multisubstructure and also provide a direct evidence of Fermi resonances which were predicted to be a major feature of H‐bonds. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010