Dipole moment matrix for vibration - rotation transitions in C3v molecules

The transformed dipole moment or C3v molecules has been worked out up to second order of approximation on the basis of its invariance properties. Its dependence on the total angular momentum components has been made explicit. The dipole moment matrix has been written with a view to calculate vibration-rotation intensities in the case of strongly interacting vibrational polyads. The importance of a coherent phase system for correct intensity calculations has been emphasized.Le moment dipolaire transformé des molécules C3v a été calculé jusqu'au second ordre d'approximation sur la base de ses propriétés d'invariance. Sa dépendance par rapport aux composantes du moment angulaire total a été explicitée. La matrice moment dipolaire a été écrite pour permettre le calcul des intensités de vibration-rotation dans le cas des polyades vibrationnelles fortement interagissantes. L'importance de la cohérence des facteurs de phase pour un calcul rigoureux des intensités a été soulignée

On the local mode behaviour of the XH2/XD2 and XD/XH fragments with respect to the deuterated species of the near local mode XH3(C3v ) molecule

International audienceEffect of isotopic substitution in the near local mode, XH3(C3v), molecules is considered. On that basis it is shown that the spectroscopic properties of deuterated and/or di-deuterated isotopic species of the XH3(C3v) molecule with the value of interbond angle close to π/2 are analogous to the spectroscopic properties of its separate fragments: of a three-atomic local mode 'molecule' XH2/XD2 and of a diatomic XD/XH 'molecule'. The phosphine molecule is considered as an illustration

On the study of the vibrational energy levels of Arsine molecule

International audienceWe compare two formalisms applied to the vibrational modes of the molecule of AsH3 of C3v molecular symmetry group. Indeed, the close stretching modes of this molecule may be considered as those of a three-dimensional oscillator whereas the bending modes may be considered either as a one-dimensional oscillator of symmetry A1 and a two-dimensional oscillator of symmetry E or as an approximate three-dimensional oscillator. So, we have applied the U(p + 1) formalism to the both stretching and bending modes and introduced coupling terms acting on an appropriate coupled vibrational basis through a local mode formalism. We have then compared the result of our fitting with those obtained with the coupling of a local mode formalism adapted to the stretching vibrations with a normal mode formalism for the bending ones. Finally we compare our results with other methods recently proposed in the literature

On the determination of the intramolecular potential functions for a polyatomic molecule : H2S

International audienceOne of the most important problems of modern molecular physics connected with the study of vibrational-rotational spectra of molecules is the problem of determining the intramolecular potential function (IMPF) of molecules. This problem is important primarily because the knowledge of the potential function is the key point for a solution of the Schrödinger equation

Oб определении внутримолекулярной потенциальной функции многоатомной молекулы H2S

In modern molecular physics, there are two basic methods of determining the intramolecular potential function of polyatomic molecules. The first method is ab initio calculations and the second is the so-called semi-empirical method in which the Hamiltonian parameters are varied by direct construction of the Hamiltonian matrix. In the present work, the second approach is discussed on the example of the XY2 three-atomic molecule of the C2v symmetry. On the one hand, it is extremely simple for implementation, and on the other hand, it considerably extends the capability of application of the traditional semi-empirical methods. The approach suggested involves two aspects that make it advantageous in comparison with traditional approaches: a) the developed calculation scheme of diagonalization of matrices of huge dimensions and b) introduction of such vibrational coordinates that allow both the kinetic part of the Hamiltonian and the potential function to be expressed in a very simple form