title: Potential energy surface for H2O((3)A(")) from accurate ab initio data with inclusion of long-range interactions.
abstract: A new potential energy surface for the O((3)P) + H(2) system in the lowest (3)A(") state is built using ab initio data calculated by Rogers et al. [J. Phys. Chem. A 104, 2308 (2000)] and the double many-body expansion formalism. It incorporates a semiempirical model of long-range interactions, which should play an important role at low collision energies. Preliminary quasiclassical trajectory results at 12.6 kcal/mol collision energy, show that the deeper van der Waals region described in this new surface translates into a four times higher cross section than that of Rogers' (3)A(") surface. To confirm this hypothesis, a second surface was calibrated. The two surfaces are fitted with rmsd<0.5 kcal/mol and differ mainly on the depth of the van der Waals region. That difference in the van der Waals region corresponds to a 22% lower cross section of the less deep surface, which is still three times higher than the equivalent results from Rogers' (3)A(") surface. This study reflects the importance of a correct description of van der Waals forces on potential energy surfaces.
authors.affiliation: Departamento Química e Bioquímica-FCT, Universidade do Algarve, Campus de Gambelas, 8005-139 FARO, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Brandão
authors.forename: César
authors.initials: C
authors.lastname: Mogo
authors.forename: Bruno C
authors.initials: BC
authors.lastname: Silva
mesh_terms: D000465:Algorithms; D016880:Anisotropy; D002138:Calibration; D002627:Chemistry, Physical / Q000379:methods*; D008956:Models, Chemical; D015233:Models, Statistical; D008962:Models, Theoretical; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water