ADVANCED WORKSHOP ON THEORETICAL AND COMPUTATIONAL METHODS FOR
MOLECULAR SPECTROSCOPY AND COLLISIONS: APPLICATION TO ASTROPHYSICAL
AND ATMOSPHERICAL RELEVANT SYSTEMS
Granada 7th – 10th May 2009
Interactions, bound states, and collision dynamics of O2
+O2: an ab initio study
Marta I. Hernández 1,*, Massimiliano Bartolomei1, Estela CarmonaNovillo1, Jesús Pérez Ríos1, José Campos Martínez1, Fabrice Dayou2
and Ramón Hernández-Lamoneda3
1
Instituto de Física Fundamental, Consejo Superior de Investigaciones
Científicas, C/ Serrano 123, Madrid 28006, SPAIN
2
Centro de Investigaciones Químicas, Universidad Autónoma del
Estado de Morelos, Cuernavaca, 62210, Mor. MEXICO
3
Laboratoire d'Etude du Rayonnement et de la Matière en
Astrophysique, UMR 8112 du CNRS, Observatoire de Paris-Meudon, 5
place Jules Janssen, 92195 Meudon Cedez, FRANCE

marta@imaff.cfmac.csic.es
1. Field of activity and interest
We are interested in the understanding -from first principles- of processes
involving small molecules of importance in atmospheric/astrophysical sciences.
Our aim is assisting in the interpretation of observations or experiments by
means of accurate simulations of the interactions and of the spectroscopy or
dynamics. In particular, we have been focused in the study of the interactions
between oxygen molecules, which are not only of interest in several different
processes in the atmosphere (involving different electronic states), but also in
condensed matter studies and, more recently, in ultracold conditions.
2. Methodologies
Obtention of potential energy surfaces (PES) and couplings (spin-orbit or radial
non-adiabatic) by means of highly correlated electronic structure methods.
Simulations of the collision dynamics by means of time-independent closecoupling or wave packet methods. Basis sets representation for the calculation
of bound or quasibound states. Codes used include MOLPRO, MOLCAS,
GAMESS, DALTON,.., for the electronic calculations and MOLSCAT,
MOLCOL, BOUND, as well as domestic ones for the nuclear dynamic
calculations.
3. Main results
We will report recent progress in the computation of realistic PESs for the three
lowest states (with spin multiplicity one, three and five) correlating with
O2(3 -)+ O2(3 -). For the quintet PES, the accurate RCCSD(T) method was
g
g
employed, considering a large number of relative orientations and
intermolecular distances [1]. The calculation of the singlet and triplet PESs
cannot be performed with the same level of accuracy with present
methodologies. In these cases, we have built the PESs by adding, to the
RCCSD(T) quintet PES, singlet-quintet and triplet-quintet splittings computed
at the MRCI or CASPT2 levels [2]. The new PESs are tested against a variety
of experiments by the computation of second virial coefficients, bound states, as
well as rotational energy transfer collision dynamics [3].
Finally, we would like to briefly report on studies of electronic energy transfer
in O2 + O2 collisions, of relevance in the terrestrial atmosphere. On the one
hand, we have investigated the effect of spin-orbit couplings in the depletion
rates of O2(3 -,v>19) by O2(3 -,v'=0) and found that, for v>27, energy transfer
g
g
to the 1 - excited state becomes very efficient, providing in this way an
g
explanation for experimental observations [4]. On the other hand, we have been
studying electronic energy transfer in O2(1 -,v>0) + O2(3 -,v'=0) collisions
g
g
by the calculation of non-adiabatic radial couplings, and have achieved
qualitative agreement with observations regarding the dependence of the
deactivation rates with v and temperature [5].
4. Projects
We are interested in pursuing ab initio studies of processes involving small
open-shell dimers of relevance in atmospheric and/or astrophysical contexts, as
well as in ultracold conditions.
Acknowledgments
Financial support by Spanish grant CTQ2007-62898-BQU and by
Mexican CSIC-CONACYT program (2005MX0025) is acknowledged.
Spanish-
References
1. M. Bartolomei, E. Carmona-Novillo, M. I. Hernández, J. Campos-Martínez,
R. Hernández-Lamoneda, J. Chem. Phys. 128, 214304 (2008).
2. M. Bartolomei, M. I. Hernández, J. Campos-Martínez, E. Carmona-Novillo, R.
Hernández Lamoneda, Phys. Chem. Chem. Phys. 10, 5374 (2008).
3. M. Bartolomei, J. Pérez Ríos, E. Carmona-Novillo, M. I. Hernández, J.
Campos-Martínez, R. Hernández-Lamoneda, in preparation (2009)
4. F. Dayou, M. I. Hernández, J. Campos-Martínez, R. Hernández-Lamoneda, 126
194309 (2007)
ADVANCED WORKSHOP ON THEORETICAL AND COMPUTATIONAL METHODS FOR
MOLECULAR SPECTROSCOPY AND COLLISIONS: APPLICATION TO ASTROPHYSICAL
AND ATMOSPHERICAL RELEVANT SYSTEMS
Granada 7th – 10th May 2009
5.
F. Dayou, M. I. Hernández, J. Campos-Martínez, R. Hernández-Lamoneda, in
preparation (2009).