Institut des Sciences Moléculaires d'Orsay



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Theoretical methods

Vibrational structure and dynamics

Structure, dynamics and vibrational spectroscopy (IR, IRMPD, IR-2D, Raman) of molecules in the ground electronic state are analysed from different theoretical strategies at the atomic scale. Most of the algorithms and methods we use are developed within our group.
For hydrocarbonated molecules, quantum chemistry (DFT), semi-empirial (Tight-Binding) or empirical reactive (AIREBO) potentials are used to build their potential energy surfaces (PES). As these PES are complex (large number of (…)

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Non-rigid molecules

A significant portion of the molecules dealt with in the team are non-rigid molecules displaying large amplitude motions. For these molecules a specific treatment is necessary as their vibrational energies cannot be obtained using the harmonic approximation nor
can their rotational energies be calculated using the rigid rotator approach.
To treat such molecules, 4-D models are used in which the large amplitude motion and the overall rotation are treated simultaneously. Such models were (…)

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