We consider a system of coupled harmonic oscillators on a cubic lattice. The force constants are supposed to take two distinct values at random according to a bond concentration x. The density of states (DOS) is evaluated both by numerical diagonalisation and in coherent-potential approximation (CPA). There is excellent agreement between the results of the two methods. Near the concentration, w...

We introduce a scheme to obtain the deconvolved density of states (DOS) of the tip and sample, from scanning tunneling spectra determined in the constant-current mode (z-V spectroscopy). The scheme is based on the validity of the Wentzel-Kramers-Brillouin (WKB) approximation and the trapezoidal approximation of the electron potential within the tunneling barrier. In a numerical treatment of z-V...

We consider a tight-binding Hamiltonian defined on the quasiperiodic Ammann-Beenker tiling. Although the density of states (DOS) is rather spiky, the integrated DOS (IDOS) is quite smooth and can be used to perform spectral unfolding. The effect of unfolding on the integrated level-spacing distribution is investigated for various parts of the spectrum which show different behaviour of the DOS. ...

We consider a tight-binding Hamiltonian deened on the quasiperi-odic Ammann-Beenker tiling. Although the density of states (DOS) is rather spiky, the integrated DOS (IDOS) is quite smooth and can be used to perform spectral unfolding. The eeect of unfolding on the integrated level-spacing distribution is investigated for various parts of the spectrum which show diierent behaviour of the DOS. Fo...

We present first principles calculations of the electronic structure of small carbon nanotubes with different chiral angles theta and different diameters (d<1 nm). Results are obtained with a full potential method based on the density functional theory (DFT), with the local density approximation (LDA). We compare the band structure and density of states (DOS) of chiral nanotubes with those of z...

We have performed density functional theory investigations on the adsorption properties of ammonia molecule on the undoped and N-doped TiO2 anatase nanoparticles. We have geometrically optimized the constructed undoped and N-doped nanoparticles in order to fully understand the adsorption behaviors of ammonia molecule. For TiO2 anatase nanoparticles, the binding site is preferentially located on...

We have performed density functional theory investigations on the adsorption properties of ammonia molecule on the undoped and N-doped TiO2 anatase nanoparticles. We have geometrically optimized the constructed undoped and N-doped nanoparticles in order to fully understand the adsorption behaviors of ammonia molecule. For TiO2 anatase nanoparticles, the binding site is preferentially located on...