6533b85ffe1ef96bd12c17ca

RESEARCH PRODUCT

On the 'expanded local mode' approach applied to the methane molecule: isotopic substitution CH2D2 <--- CH4

subject

description

International audience; On the basis of a compilation of the 'expanded local mode' model and the general isotopic substitution theory, sets of simple analytical relations between different spectroscopic parameters (harmonic frequencies, anharmonic coefficients, ro-vibrational coefficients, different kinds of Fermi- and Coriolis-type interaction parameters) of the CH2D2 molecule are derived. All of them are expressed as simple functions of a few initial spectroscopic parameters of the mother, CH4, molecule. Test calculations with the derived isotopic relations show that, in spite of a total absence of initial information about the CH2D2 species, the numerical results of the calculations have a very good correlation both with experimental data, and results of ab initio calculations.