Optical absorption spectra of C70 and C76 are calculated by a tight binding model with a long ranged Coulomb interaction. The spectrum of C70 is in overall agreement with the experiment of molecules in a solution. The variations of the spectral shape are discussed relating with the symmetry reduction from C70 to C76.

Tight triangulated manifolds are generalisations of neighborly triangulations of closed surfaces and are interesting objects in Combinatorial Topology. Tight triangulated manifolds are conjectured to be minimal. Except few, all the known tight triangulated manifolds are stacked. It is known that locally stacked tight triangulated manifolds are strongly minimal. Except for three infinite series ...

The possible formation of a “cluster molecule” (C20)2 from two single C20 fullerenes is studied by the tight-binding method. Several (C20)2 isomers in which C20 fullerenes are bound by strong covalent forces and retain their identity are found; actually, these C20 fullerenes play the role of “atoms” in the “cluster molecule”. The so-called open-[2+2] isomer has a minimum energy. Its formation p...

We carry out a careful study of basic topological and ergodic features of Delone dynamical systems. We then investigate the associated topological groupoids and in particular their representations on certain direct integrals with non constant fibres. Via non-commutative-integration theory these representations give rise to von Neumann algebras of random operators. Features of these algebras and...

The interplay of local energetics, local electron occupancies, and local density of states is the key to the understanding of chemical reactivity. We define local measures, within a nonorthogonal tight-binding scheme, which clearly and unambiguously determine these local properties for an aggregate of atoms, such as a solid or a cluster. Using these measures, we identify the electronic level me...

We present the first application of time-dependent density functional tight-binding method to rationalize photo-induced electron transfer in an experimental hexyl-protected Au25 cluster labeled with a pyrene fluorophore.

We explore the collective electromagnetic response in atomic clusters of various sizes and geometries. Our aim is to understand, and hence to control, their dielectric response based on a fully quantum-mechanical description which captures accurately their relevant collective modes. The electronic energy levels and wave functions, calculated within the tight-binding model, are used to determine...

We demonstrate for the first time a tight binding model for water incorporating polarizable oxygen atoms. A novel aspect is that we adopt a "ground up" approach in that properties of the monomer and dimer only are fitted. Subsequently we make predictions of the structure and properties of hexamer clusters, ice-XI and liquid water. A particular feature, missing in current tight binding and semie...

We calculate the transverse effective charges of zinc-blende compound semiconductors using Harrison’s tight-binding model to describe the electronic structure. Our results, which are essentially exact within the model, are found to be in much better agreement with experiment than previous perturbation-theory estimates. Efforts to improve the results by using more sophisticated variants of the t...

Artificial graphene consisting of honeycomb lattices other than the atomic layer of carbon has been shown to exhibit electronic properties similar to real graphene. Here, we reverse the argument to show that transport properties of real graphene can be captured by simulations using "theoretical artificial graphene." To prove this, we first derive a simple condition, along with its restrictions,...