Strong Closed-Shell Interactions in Inorganic Chemistry.

This review describes a multidimensional treatment of molecular recognition phenomena involving aromatic rings in chemical and biological systems. It summarizes new results reported since the appearance of an earlier review in 2003 in host-guest chemistry, biological affinity assays and biostructural analysis, data base mining in the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB), and advanced computational studies. Topics addressed are arene-arene, perfluoroarene-arene, S⋅⋅⋅aromatic, cation-π, and anion-π interactions, as well as hydrogen bonding to π systems. The generated knowledge benefits, in particular, structure-based hit-to-lead development and lead optimization both in the pharmaceutical and in the crop protection industry. It equally facilitates the development of new advanced materials and supramolecular systems, and should inspire further utilization of interactions with aromatic rings to control the stereochemical outcome of synthetic transformations.

Aromatic rings in chemical and biological recognition: energetics and structures.

Fragmentation Methods: A Route to Accurate Calculations on Large Systems Mark S. Gordon,* Dmitri G. Fedorov, Spencer R. Pruitt, and Lyudmila V. Slipchenko Department of Chemistry and Ames Laboratory, Iowa State University, Ames Iowa 50011, United States Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States

Fragmentation methods: a route to accurate calculations on large systems.

Electron dispersion forces play a crucial role in determining the structure and properties of biomolecules, molecular crystals, and many other systems. However, an accurate description of dispersion is highly challenging, with the most widely used electronic structure technique, density functional theory (DFT), failing to describe them with standard approximations. Therefore, applications of DFT to systems where dispersion is important have traditionally been of questionable accuracy. However, the last decade has seen a surge of enthusiasm in the DFT community to tackle this problem and in so-doing to extend the applicability of DFT-based methods. Here we discuss, classify, and evaluate some of the promising schemes to emerge in recent years. A brief perspective on the outstanding issues that remain to be resolved and some directions for future research are also provided.

Perspective: Advances and challenges in treating van der Waals dispersion forces in density functional theory.

Electron dispersion forces play a crucial role in determining the structure and properties of biomolecules, molecular crystals and many other systems. However, an accurate description of dispersion is highly challenging, with the most widely used electronic structure technique, density functional theory (DFT), failing to describe them with standard approximations. Therefore, applications of DFT to systems where dispersion is important have traditionally been of questionable accuracy. However, the last decade has seen a surge of enthusiasm in the DFT community to tackle this problem and in so-doing to extend the applicability of DFT-based methods. Here we discuss, classify, and evaluate some of the promising schemes to emerge in recent years. A brief perspective on the outstanding issues that remain to be resolved and some directions for future research are also provided.

Perspective: Advances and challenges in treating van der Waals dispersion forces in density functional theory

The method of increments—a wavefunction-based ab initio correlation method for solids

The electronic structure of the zero-gap two-dimensional graphene has a charge neutrality point exactly at the Fermi level that limits the practical application of this material. There are several ways to modify the Fermi-level-region of graphene, e.g. adsorption of graphene on different substrates or different molecules on its surface. In all cases the so-called dispersion or van der Waals interactions can play a crucial role in the mechanism, which describes the modification of electronic structure of graphene. The adsorption of water on graphene is not very accurately reproduced in the standard density functional theory (DFT) calculations and highly-accurate quantum-chemical treatments are required. A possibility to apply wavefunction-based methods to extended systems is the use of local correlation schemes. The adsorption energies obtained in the present work by means of CCSD(T) are much higher in magnitude than the values calculated with standard DFT functional although they agree that physisorption is observed. The obtained results are compared with the values available in literature for binding of water on the graphene-like substrates.

On the physisorption of water on graphene: a CCSD(T) study

The incremental scheme for obtaining the energetic properties of extended systems from wave-function-based ab initio calculations of small (embedded) building blocks, which has been applied to a variety of van der Waals-bound, ionic, and covalent solids in the past few years, is critically reviewed. Its accuracy is assessed by means of model calculations for finite systems, and the prospects for applying it to delocalized systems are given.

On the accuracy of correlation-energy expansions in terms of local increments.

In order to gain more insight into factors governing the relative stability of the fcc and hcp structures of the rare-gas solids Ne through Xe, we performed ab initio coupled-cluster calculations for the most important three- and four-body terms in the many-body expansion of the cohesive energy. These terms are combined with empirical two-body potentials derived from dimer data and with a multipole expansion for the long-range three-body terms. In addition, we calculated phonon spectra, in harmonic approximation, for the two structures. Including zero-point energies, our results agree very well with experimental data for the fcc structure. The hypothetical hcp structure, which is lower in energy with two-body potentials, is destabilized by short-range three-body terms and, even more important, by the contribution of zero-point vibration.

Ab initio coupled-cluster calculations for the fcc and hcp structures of rare-gas solids

Cohesive energies, lattice constants, and bulk moduli have been calculated for the rare-gas crystals Ne through Xe. The results are based on a many-body expansion of the interaction energy, with two- and three-atom contributions evaluated in valence-only coupled-cluster calculations using relativistic pseudopotentials. Although the two-body contributions dominate the cohesive energy in all cases, the influence of three-body contributions is non-negligible and reaches nearly 7% of the cohesive energy for Xe.

Beate Paulus

Papers

The method of increments—a wavefunction-based ab initio correlation method for solids

On the physisorption of water on graphene: a CCSD(T) study

On the accuracy of correlation-energy expansions in terms of local increments.

Ab initio coupled-cluster calculations for the fcc and hcp structures of rare-gas solids

Ab initio calculation of ground-state properties of rare-gas crystals.