**5. Conclusions**

In Sections 2 and 3, we have discussed the influence of quantum correlations on the formation of tightly bound solids. Section 2 is devoted to the effects of the overlaps and neglected multicenter integrals on tight-binding band spectra. An exact calculation in the framework of a simple atomic model has shown that they shift *unevenly* the top and bottom of the band spectrum (their effects are more pronounced at the top). Section 3 introduced a quantum Monte Carlo method specific for strongly correlated fermion systems. Section 4 addressed the stochastic

## *Issues in Solid-State Physics DOI: http://dx.doi.org/10.5772/intechopen.84367*

dynamics of a ring of FHN cells—with nearest neighbor *electric* (diffusive) coupling between their *inhibitor* fields—undergoing spatiotemporal pattern formation induced by noise and coupling. By means of a simple model for which a NEP can be found, the mechanism whereby the process takes place was investigated analytically.
