Calculations based on density functional theory demonstrate the occurrence of local deformations of the perfect honeycomb lattice in nanographenes to form arrangements, with triangular symmetry, composed of six-membered ring patterns. The formation of these locally regular superstructures, which can be considered as benzenoid-like domains on the 2D graphene lattice, is ascribed to the gain in r...

The discovery of high-Tc superconductivity in the cuprates, and the observation that strong correlations are important in connection with these compounds has led to a tremendous interest in understanding the physics of strongly correlated electronic models. In particular the two simplest models for strongly correlated electrons, namely the Hubbard and t−J models, have been the subject of intens...

The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters. Theory of Néel and valence-bond-solid phases on the kagome lattice of Zn-paratacamite. Recently, neutron scattering data on powder samples of Zn-paratacamite, ZnxCu4−x(OH)6Cl2, with small Zn concentration has been interpreted as evidence for valence bond solid and Néel or...

This paper gives a brief history of the establishment of relations between electronic structure and chemical reactivity of molecules obtained by using quantum mechanical techniques. After a short introduction devoted to the qualitative period a more important part of the paper is concerned with the discussion of the methods which permit some estimations of the constant rates. Both static and dy...

The strongly correlated two-dimensional Cu0& layer is studied to identify the mechanism of possible pairing superconductivity. The correlative motions of 0 and Cu holes are treated by a reasonable mean-field theory, and we find that holes on oxygen sites couple strongly to Cu holes to form Cu-0 spin singlet pairs, which in turn interact strongly with the Cu resonating-valence-bond state and lea...