Articles you may be interested inOn the use of explicitly correlated treatment methods for the generation of accurate polyatomic -He/H2 interaction potential energy surfaces: The case of C3-He complex and generalization J. Chem. Phys. 141, 044308 (2014); 10.1063/1.4890729Ab initio potential energy surface and nearinfrared spectrum of the He-C2H2 complex Energy separation between the open (C 2v ) and closed (D 3h ) forms of ozone Ab initio molecular orbital calculations have been used to study the most important features of the potential energy surfaces corresponding to Li ϩ association to C 2v and D 3h ozone. For this purpose highly correlated techniques ͓CASSCF, QCISD, and QCISD͑T͔͒ have been used. Our results confirm that these highly correlated techniques are unavoidable in so far as a correct description of ozone-Li ϩ complexes is needed. Good agreement between CASSCF and QCI results is attained for C 2v ozone when the UHF function is taken as the reference function and triple excitations are considered in the QCI treatment. Results for D 3h ozone are in agreement only when a proper description of the correlation is included in the CASSCF treatment. Interactions with Li ϩ are stronger for open chain ozone than for the cyclic isomer. Thus on complex formation the energy gap between C 2v and D 3h ozone increases. There exist three structures which are predicted to lie very close in energy. The global energy minimum corresponds to an isomer in which the Li ϩ bridges both terminal oxygens, but other structures corresponding to the attachment of Li ϩ to one of the terminal oxygens and to an insertion of the Li ϩ in one of the O-O bonds, respectively, are about 1 kcal/mol less stable.