Search

The electronic structure of the toroid D$_{6h}$-Au$_{42}$ is studied within the framework of the Hubbard Hamiltonian in the approximation of static fluctuations. An expression for the Fourier transform of the Green's function, the poles of which determine the energy spectrum of the nanocluster under consideration, is obtained. The energy spectrum of the D$_{6h}$-Au$_{42}$ toroid indicates that the nanosystem is in a metallic state. Graphical representations of the equation for the chemical potential and the density of state of electrons are presented. The spectrum of optical absorption is shown, the energies of direct optical transitions D$_{6h}$-Au$_{42}$ are 0.95 eV, 1.24 eV, 1.39 eV, are in the near infrared region. The energy of the ground state is calculated for the electrically neutral as well as for the positively and negatively charged ions of the toroid. The possibility of using of the investigated toroid from Au atoms for the diagnostics and treatment of cancer is shown., Comment: 6 pages including drawings

The electronic structure of chair-type biphenylene ribbons is studied within the framework of the Hubbard Hamiltonian in the approximation of static fluctuations. An expression is obtained for the Fourier transform of the Green's functions, whose poles determine the spectrum of elementary excitations. The energy spectrum of biphenylene ribbons indicates that nanoribbons with a width of 6, 9, 12, 15, 18 carbon atoms are in the semiconductor state. Densities of state of electrons of biphenylene ribbons of various widths are presented in comparison with the results of experimental measurements of differential conductance of biphenylene ribbons. It is shown that the width of the band gap decreases exponentially with an increase in the width of the biphenylene ribbon. Ribbons with a width of 21 carbon atoms or more are in the metallic state., Comment: 17 pages (including 7 figures)