Topological Approaches to Intermolecular Interactions

26-28 June 2013 - Paris

Workshop on "Topological approaches to intermolecular interactions"

Non-Covalent Interaction Analysis in Fluctuating Environments and Exchange-Correlation Energies from Response Properties

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Abstract

To apply the NCI analysis to fluctuating environments as in solution phase, we developed a new Averaged NonCovalent Interaction (i.e., aNCI) index along with a fluctuation index to characterize magnitude of interactions and fluctuations. We applied aNCI for various systems including solute-solvent and ligand-protein noncovalent interactions. For water and benzene molecules in aqueous solution, solvation structures and the specific hydrogen bond patterns were visualized clearly. For the Cl-+CH3Cl SN2 reaction in aqueous solution, charge reorganization influences over solvation structure along SN2 reaction were revealed. For ligand-protein systems, aNCI can recover several key fluctuating hydrogen bond patterns that have potential applications for drug design. Therefore, aNCI, as a complementary approach to the original NCI method, can extract and visualize noncovalent interactions from thermal noise in fluctuating environments.

In the second part of the talk, we will present an adiabatic connection to formulate the exchange-correlation energy in terms of response properties. This formulation of the exchange-correlation energy opens new channels for density functional approximations based on the many-body perturbation theory. We illustrate the potential of such approaches with an approximation based on the Random Phase Approximation. This resulting method has many highly desirable properties. It has minimal delocalization error with a nearly linear energy behavior for systems with fractional charges, describes van der Waals interactions similarly and thermodynamic properties significantly better than the conventional RPA, and eliminates static correlation error for single bond systems. Most significantly, it is the first known functional with an explicit and closed-form dependence on the occupied and unoccupied orbitals that captures the energy derivative discontinuity in strongly correlated systems.


Speaker(s) : Weitao Yang, Department of Chemistry, Duke University, Durham, N.C. 27708, U.S.A.
Public : Tous
Date : June 28 2013
Place : Paris