Theoretical study of molecular properties of low-lying electronic excited states of H₂O and H₂S

Jana Páleníková (1) , Michal Kraus (1) , Pavel Neogrády (1) , Vladimir Kellö (1) , Miroslav Urban (1)

1 Department of Physical and Theoretical Chemistry

Geometries, excitation energies, dipole moments and dipole polarizability tensor components of the ground and four lowest excited states ³B₁, ¹B₁, ³A₂, ¹A₂ of the H₂O and H₂S molecules were calculated at the CASSCF, CASPT2, CCSD and CCSD(T) level of approximation. Vertical excitation and equilibrium transition energies of these states, having the Rydberg character, are reported too. Properties of both molecules in the ground and in low lying excited states are compared and discussed from the point of view of their molecular electronic structure. Upon excitation we observe dramatic changes of dipole moments and polarizabilities with respect to the ground state. We stress the change of the polarity of H₂O in all excited states accompanied by the enhancement of the dipole polarizability by an order of magnitude. Large, even if less pronounced, are changes of electric properties of H₂S in its excited states. Dipole moments and dipole polarizabilities of ³B₁, ¹B₁ states of H₂S and H₂O behave quite analogously in comparison to their respective ground state. General pattern of properties of both molecules in their ³A₂ and ¹A₂ excited states is more different due to pronounced participation of the sulphur d-orbitals in these states of the H₂S molecule.

Mots clés: Physical Sciences

Jana Páleníková, Michal Kraus, Pavel Neogrády, Vladimir Kellö, Miroslav Urban. Theoretical study of molecular properties of low-lying electronic excited states of H₂O and H₂S. Molecular Physics, 2008, 106 (20), pp.2333-2344. ⟨10.1080/00268970802454786⟩. ⟨hal-00513229⟩