Colloquium 10/25/13 - Interactions of atoms, molecules, and surfaces-pushing the limits of accuracy.

The knowledge of weak interaction energies between atoms or molecules is crucial for understanding the properties of clusters, liquids, crystals, and biomolecules. The intermolecular interaction energies are small (typically on the order of 0.1 eV) and extremely sensitive to virtually all details of the quantum-chemical calculation, including both the one-electron basis set and the treatment of electron correlation. I will present several examples from our group's research where accurate interaction energies were obtained for complexes ranging from He-H2 all the way to methane-carbon nanotube. The requirements for obtaining accurate interaction energies will be illustrated and explored.