246 research outputs found
High Level Theoretical Investigation of Binding and Potential Energy Surfaces in Ion-Aromatic System Complexes
No full text
High level theoretical study of binding and of the potential energy surface in benzene–hydride system
No full textHigh level ab initio calculations were performed on the interaction of the hydride anion with benzene, a
system of potential interest for modelling the interactions occurring in hydrogen rich planetary atmospheres.
We investigated both non-covalent and covalent binding, exploring the complete basis set limit
using highly correlated MP2 and CCSD(T) levels of theory. Two non-covalent minima on the potential
energy surface have been characterized, and found to correspond to moderately strong hydrogen bonding
interactions. To gain further insight on the nature of binding, the total interaction energy was decomposed
into its physically meaningful components and selected sections of the potential energy surface
were calculated. Moreover, we found that H can easily covalently bind to one of the carbon atoms of
benzene to form a stable C6H7 anion, a global minimum on the potential energy surface, characterized
by a puckered geometry, with a carbon atom bending out of the benzene plane. A slightly less stable planar
C6H7 structure was also identified, corresponding to the transition state for the flipping motion of
the puckered species
Theoretical study of alkali cation-benzene complexes: Potential energy surfaces and binding energies with improved results for rubidium and cesium
No full text
Quantum-classical calculation of cross sections and rate constants for the H2+CN→HCN+H reaction
No full textPerformance of DFT and MP2 Approaches for Geometry of Rhenium Allenylidenes Complexes and the Thermodynamics of Phosphines Addition
No full textThe performance of density functional theory (DFT) and Møller-Plesset perturbation second order theory (MP2) for prediction of the geometry of an important class of rhenium complexes and the thermodynamics of their reaction with nucleophiles has been assessed. In particular, we addressed the rhenium(I) allenylidene [(triphos)(CO)2Re(=C=C=CPh2)] + species [triphos = MeC(CH2PPh2)3] and its reaction toward tertiary phosphines. Several exchange-correlation functionals were tested and the results indicate that the usually employed GGA and hybrid functionals, such a BP86, BLYP, B3LYP and PBE while correctly predicting the geometry of these species, qualitatively and quantitatively fail to reproduce the thermodynamics for the addition of the phosphine nucleophiles, especially the first three ones, with errors up to 30 kcal mol− 1. Reasonable results, qualitatively in agreement with experimental evidence, can be obtained only through the use of a correlated wavefunction approach such as MP2 or of the more recently developed functionals M06 and M06-L
- …
