S. Oss

Algebraic approach to molecular spectra: Two‐dimensional problems

The Lie algebraic approach is extended to two‐dimensional problems (rotations and vibrations in a plane). Bending vibrations of linear polyatomic molecules are discussed. The algebraic approach is particularly well suited to treat coupled bending modes. The formalism needed to treat coupled benders is introduced and a sample case, acetylene, is analyzed in terms of two coupled local benders.

Overtone frequencies and intensities of bent XY2 molecules in the vibron model

Abstract Calculations of overtone frequencies of five bent XY 2 molecules, H 2 O 16 , H 2 O 18 , D 2 O 16 , H 2 S 32 , and S 32 O 2 16 , with average rms deviations of 1–5 cm −1 are reported. The calculations are performed within the framework of the vibron model and sets of algebraic force field constants are presented. The corresponding wavefunctions are used to calculate intensities in the H 2 O 16 molecule. The calculated intensities are compared with recent measurements of the ATMOS collaboration.

Vibrational spectroscopy and intramolecular relaxation of benzene

By making use of Lie algebraic methods, we construct the complete vibrational spectrum of benzene. We use this construction to study the process of intramolecular vibrational energy relaxation in the first and second overtone of the CH stretching mode.

Vibrational spectra of linear triatomic molecules in the vibron model

Abstract We report results of calculations of five linear triatomic molecules, N 2 O, C 12 O 2 , C 13 O 2 , OCS, and HCN, with average r.m.s. deviations of 1–5 cm −1 within the framework of the vibron model. The corresponding algebraic force field constants are derived. Calculations of intensities of stretching vibrations in CO 2 and HCN are also presented.

Linear four-atomic molecules in the vibron model

Abstract We present a general scheme for calculating spectra of linear four-atomic molecules and apply it to the study of acetylene, C 2 H 2 , and its isotopic variations, C 2 D 2 and C 2 HD. Particular emphasis is given to the phenomenon of l -splitting, which plays an important role in four-atomic molecules. We are able to describe all known experimental levels, including stretching and bending, with an average rms of 10 cm −1 .

Algebraic model of bending vibrations of complex molecules

Abstract We introduce an algebraic model of coupled anharmonic benders capable of describing the complete spectrum and intensities of bending vibrations of medium size and large polyatomic molecules. We apply this model to the calculation of CH bends in C 6 H 6 . The model appears to describe the data well.

Vibrational modesoof polyatomic molecules in the vibron model

Abstract We introduce an algebraic model of vibrations of polyatomic molecules and present, as an example, the vibrational analysis of CH and CD stretching modes of benzene, C6H6, and its deuterated forms C6H6-nDn (n = 1–6). Our analysis suggests some reassignments of levels and predicts location of states not yet observed. It also provides a set of algebraic force field constants which can be used for further studies of benzene.

Stretching vibrations of benzene in the algebraic model

Abstract We introduce an algebraic model of coupled anharmonic oscillators capable of describing the complete spectrum and intensities of X-Y stretching vibrations of medium size and large polyatomic molecules. We apply this model to the calculation of CH and CD stretches of C 6 H 6 and C 6 D 6 . The model appears to describe the data accurately.

Quasi-linear four-atomic molecules in the vibron model

Abstract We study the transition from linear to bent four-atomic molecules within the framework of the vibron model. We consider quasi-linear molecules and analyze the “classcal” case of fulminic acid (HCNO). The algebraic force-field constants we obtain can be used to make predictions for further investigations of this molecule.

Vibrational spectroscopy of CH/NH stretches in pyrrole: An algebraic approach

The complete vibrational spectroscopy of pyrrole is addressed within the one-dimensional algebraic framework. Particular attention is devoted to the study of the CH/NH stretching levels, including their possible anharmonic resonance mechanisms with other ring modes.