Oligoacenes are basic compounds of hydrogen and carbon, which look like linearly fused hexagonal rings: (a) Examples of oligoacenes: benzene (N=1), anthracene (N=3) and hexacene (N=6). (b) Dependence of the excitation gap as a function of the number of rings N. There is a non-trivial period of 11 rings. (c) Emergence of the gap oscillations:
Transmission probability of a scattering electron as a function of energy. The electrode material is silver or platinum Molecular bridge: pentacene Calculated by atomistic first-principles calculations Further reading: Conductance saturation in a series of highly transmitting molecular junctions T. Yelin, R. Korytár, N. Sukenik, R. Vardimon, B. Kumar, C. Nuckolls, F. Evers & O. Tal,
Section through part of a molecular junction. On the left you can see the terminal atoms of the gold electrode, represented in a ball-and-stick model with yellow balls. On the right there is part of the molecule. The red/blue bubbles display the wave function of the transmitting state – a state that carries the electric current when voltage
Computational theory of condensed matter deals with a diverse set of systems, where the common denominator is complexity. A molecule in contact with a macroscopic lead is an example. Other examples are systems with reduced dimensionality and inhomogeneous systems. These systems host a number of degrees of freedom, such as charge and spin, electrons and
