1. Computational Chemistry: From the Hydrogen Molecule to Nanostructures

Quantum chemical calculations rely on a few fortunate circumstances like usually small relativistic and negligible electrodynamic (QED) corrections and large nuclei-to-electron mass ratio. The fast progress in computer technology revolutionized theoretical chemistry and gave birth to computational chemistry. The computational quantum chemistry provides for experimentalists the ready-to-use tools of new kind offering powerful insight into molecular internal structure and dynamics. It is important for the computational chemistry to elaborate methods, which look at molecule in a multiscale way, which provide first of all its global and synthetic description such as shape and charge distribution, and compare this description with those for other molecules. Only such a picture can free researchers from seeing molecules as a series of case-by-case studies. Chemistry represents a science of analogies and similarities, and computational chemistry should provide tools for seeing this. This is especially useful for the supramolecular chemistry, which allow chemists to planify and study intermolecular interactions. Some of them, involving concave and convex moieties, represent molecular recognition, which assures a perfect fitting of the two molecular shapes. A sequence of molecular recognitions often leads to self-assembling and self-organization, typical to nanostructures.