What Is Life? information has to be both small in size and permanent in time, contradicting the naïve physicist's expectation. This contradiction cannot be resolved by classical physics. In chapter IV, Schrödinger presents molecules, which are indeed stable even if they consist of only a few atoms, as the solution. Even though molecules were known before, their stability could not be explained by classical physics, but is due to the discrete nature of quantum mechanics. Furthermore, mutations are directly linked to quantum leaps. He continues to explain, in chapter V, that true solids, which are also permanent, are crystals. The stability of molecules
Atoms in molecules have a well-defined physical basis. QTAIM recovers the central operational concepts of the molecular structure hypothesis, that of a functional grouping of atoms with an additive and characteristic set of properties, together with a definition of the bonds that link the atoms and impart the structure. QTAIM defines chemical bonding and structure of a chemical system based on the topology of the electron density. In addition to bonding, AIM allows the calculation of certain physical properties on a per-atom basis, by dividing space up into atomic volumes containing exactly one nucleus, which acts as a local attractor of the electron