TABLE OF CONTENTS Physics is the classical material science which covers two extremes: on the one hand, there is atomic or molecular physics. This system consists of one or several atoms. Because of this limited number, we are dealing with sharply defined discrete energy levels. On the other side there is solid-state physics. The assumption of an infinitely extended body with high translation symmetry also makes it open to mathematical treatment. The production of clusters (molecules with 10 to 10,000 atoms) opens a new field of physics, namely the observation of a transition between both extremes. Of course, any experimental investigation must be followed by quantum mechanical descriptions which in turn demand new tools.
Another application of quantum mechanics is the determination of stable molecules. The advance of nanotechnology raises hopes of constructing mechanical tools within human veins or organs for instance, valves, separation units, ion exchangers, molecular repair cells and depots for medication. A special aspect of medication depot is that both the container and the medicament itself would have to be nanosynthesized.
Quantum mechanics also plays a role when the geometrical dimension is equal to or smaller than a characteristic wavelength, either the wavelength of an external radiation or the de Broglie wavelength of a particle in a bound system. An example of the first case is diffraction and for the second case, the development of discrete energy levels in a MOS inversion channel.
One of the first theoretical approaches...
