ABSTRACT
I. Introduction ...................................................................................................................... 281
A. Classical and Quantum Mechanical Calculations of Force Field
and Vibrational Spectra in the Harmonic Approximation ...................................... 282
B. The Effect of Deuterium Substitution on the Vibrations Involving
Hydrogen Motion ..................................................................................................... 284
C. The Isotopic Substitution, the Potential Energy Distribution,
and the Frequency Isotopic Ratio (ISR).................................................................. 284
II. Sources of Anomalous H/D Isotope Effects in Hydrogen-Bonded Systems.................. 285
III. The Hydrogen Bond Effect on Anharmonicity of Protonic Vibrations.......................... 287
IV. Potential Energy Functions for the Proton-Stretching Vibrations .................................. 290
V. The Shape of the Potential and Evolution of IR Spectra
of Hydrogen-Bonded Systems ......................................................................................... 292
VI. Frequency Isotopic Ratio (ISR) and Its Correlation with Other Parameters
of Hydrogen Bonds .......................................................................................................... 294
VII. The Isotope Effect upon Other Spectroscopic Parameters
of Hydrogen-Bonded Systems ......................................................................................... 296
VIII. Low-Barrier Hydrogen Bonds ......................................................................................... 298
References..................................................................................................................................... 301
Vibrational spectroscopy is a sensitive probe of the potential energy surface of the molecule which
determines the dynamics of its nuclear motion. In theoretical treatment of vibrational spectra, the
Born-Oppenheimer approximation is adopted — which assumes that an effective potential for
the nuclear motion of the molecule is determined by its total electronic energy parametrized by the
stationary nuclear coordinates. The Born-Oppenheimer approximation is valid only in the vicinity
of a local minimum of this effective potential.
