51. Ab initio study of the structures and electronic states of small neutral and ionic DABCO - Arn clusters
- Author
-
Majdi Hochlaf, Roberto Linguerri, Kevin Mathivon, Laboratoire de Modélisation et Simulation Multi Echelle (MSME), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Paris-Est Marne-la-Vallée (UPEM), and Université Paris-Est Marne-la-Vallée (UPEM)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Models, Molecular ,Ab initio ,Ionic bonding ,Electrons ,DABCO ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,Isomerism ,Ab initio quantum chemistry methods ,Cluster (physics) ,Organometallic Compounds ,Computer Simulation ,Singlet state ,Physical and Theoretical Chemistry ,Argon ,Ions ,Molecular Structure ,Chemistry ,Organic Chemistry ,Computer Science Applications ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,Kinetics ,Computational Theory and Mathematics ,Excited state ,Quantum Theory ,Thermodynamics ,Atomic physics ,Ground state ,Azabicyclo Compounds - Abstract
International audience; In the present theoretical work, we investigated the stationary points (minima and transition states) on the ground state potential energy surfaces of neutral and ionic 1,4-diazabicyclo[2.2.2]octane (DABCO) - Arn 0,+1 (n=1-4) clusters. As established in our systematic work on DABCO - Ar cluster (Mathivon et al., J Chem Phys 139:164306, 2013), the (R)MP2/aug-cc-pVDZ level is accurate enough for validating the prediction of stable forms. For n = 1 and 2, further computations at the MP2/aug-cc-pVTZ level confirm these assumptions. We show that some of the already known isomers of these heteroclusters derived using lower levels of theory are not realistic. More interestingly, our work reveals that DABCO is subject to slight deformations when binding to a small number of Ar atoms. Moreover, we computed the potential energy surfaces of the lowest singlet electronic states of DABCO - Arn (n=1-3) and of DABCO+ - Arn (n=1-3), and the transition moments for the Sp (p=1-3) ← S0 neutral transitions. These electronic states are found to be Rydberg in nature. The shape of their potentials is mainly repulsive with slight stabilization in the S2 potentials. Finally, the effects of microsolvation of DABCO in Ar clusters in ground and electronic excited states are discussed. The photophysical and photochemical dynamics of these electronic states may be complex.
- Published
- 2014