title: Modeling Charge Resonance in Cationic Molecular Clusters: Combining DFT-Tight Binding with Configuration Interaction.
abstract: In order to investigate charge resonance situations in molecular complexes, Wu et al. (J. Chem. Phys. 2007, 127, 164119) recently proposed a configuration interaction method with a valence bond-like multiconfigurational basis obtained from constrained DFT calculations. We adapt this method to the Self-Consistent Charge Density-Functional-based Tight Binding (SCC-DFTB) approach and provide expressions for the gradients of the energy with respect to the nuclear coordinates. It is shown that the method corrects the wrong SCC-DFTB behavior of the potential energy surface in the dissociation regions. This scheme is applied to determine the structural and stability properties of positively charged molecular dimers with full structural optimization, namely, the benzene dimer cation and the water dimer cation. The method yields binding energies in good agreement with experimental data and high-level reference calculations.
authors.affiliation: Université de Toulouse, UPS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, 118 Route de Narbonne, F-31062 Toulouse, France, and CNRS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, F-31062 Toulouse, France.
authors.forename: Mathias
authors.initials: M
authors.lastname: Rapacioli
authors.affiliation: Université de Toulouse, UPS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, 118 Route de Narbonne, F-31062 Toulouse, France, and CNRS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, F-31062 Toulouse, France.
authors.forename: Fernand
authors.initials: F
authors.lastname: Spiegelman
authors.affiliation: Université de Toulouse, UPS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, 118 Route de Narbonne, F-31062 Toulouse, France, and CNRS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, F-31062 Toulouse, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Scemama
authors.affiliation: Université de Toulouse, UPS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, 118 Route de Narbonne, F-31062 Toulouse, France, and CNRS, LCPQ (Laboratoire de Chimie et Physique Quantiques), IRSAMC, F-31062 Toulouse, France.
authors.forename: André
authors.initials: A
authors.lastname: Mirtschink