Ab initio study of novel crystals based on fullerene C60 and carbynes

Physics of the Solid State - The density-functional theory is used to predict the existence of new carbon structures consisting of C60 fullerenes connected by linear carbon chains with different...     

A novel covalent crystal formed by carbon (6, 0) nanotubes: Structure and electronic properties

The structure of a carbon crystal formed by (6, 0) nanotubes is simulated. The electronic spectrum of the crystal is calculated by the crystalline-orbital method in the valence approximation. The band gap of the studied crystal is found to be equal to 1.3 eV.     

Tamm states and quantum dots in carbon and heteroatomic nanotubes

The electronic structure of C-BN nanotubes is discussed in the π approximation. Two types of such structures with (n,0)-tubulet topology are investigated: 1) semiinfinite C-BN and C nanotubes and 2) C-BN nanotubes, consisting of two semiinfinite BN nanotubes coupled by a ring-shaped carbon fragment C_mn. It is shown that, in the first case, energy levels (Tamm levels) whose wave functions are localized on the terminal fragment can exist under certain conditions. In the second case, bound states localized on atoms of the carbon fragment exist. It is established that if a quite extended, cylindrical, carbon cluster is present at the end of a semiinfinite BN nanotube, then such a system can be viewed as a very simple model of a quantum dot. C-BN nanotubes where the carbon fragment couples two semiinfinite BN nanotubes can also be interpreted similarly. A simple analytic method is proposed for finding the Tamm energy levels in heteroatomic nanotubes. Fiz. Tverd. Tela (St. Petersburg) 41, 1515–1519 (August 1999)     

A new crystalline form of carbon based on the C36 fullerene: Simulating its crystal and electronic structure

A new crystalline allotropic form of carbon consisting of covalently bound fullerenes C₃₆ of symmetry D _6h is suggested. The structure of the unit cell of this compound was simulated. The unit-cell parameters obtained (a=b=6.695 Å and c=6.763 Å) are close to experimental data. The band structure of the spectrum of valence electrons was calculated by the method of crystal orbitals. The bandgap was found to be ～1.9 eV. The energy-band structure of quasi-one-dimensional macromolecules [C₃₆]_n(n?1) is discussed depending on the way in which the monomers are bound in them.     

Transport properties of two-arc Aharonov-Bohm interferometers with scattering centers

A model for a broad class of Aharonov-Bohm interferometers consisting of two arcs with and without scattering centers is constructed. Explicit expressions and asymptotic relations are found for the transmission coefficient for electrons in the simplest interferometers of diverse geometry (a symmetric interferometer with scattering admixture and an Aharonov-Bohm ring with two conductors attached at a single point). The influence of the relationship between the sizes of arcs and the arrangement of potentials of scattering centers, the magnetic field flux, and the energy of electrons on transport properties of the suggested nanodevices is studied.     

Diamond-Like Films from Twisted Few-Layer Graphene

JETP Letters - The atomic and electronic structures of diamanes, i.e., diamond-like films formed by few-layer moiré graphene with a twist angle θ in 00θ and θ00θ stackings...     

Simulation of the Formation and Mechanical Properties of Layered Structures with Polymerized Fullerene-Graphene Components

JETP Letters - A new class of nanocomposites-fullerene-graphene compounds whose components are partially polymerized-has been considered. Various two- and three-dimensional covalent and molecular...     

New boron barrelenes and tubulenes

The structure of a new class of boron nanostructures—barrelenes and tubulenes—based on a boron atomic lattice constructed by the alternating B-atomic polygons with central atoms and without them has been proposed and their properties have been described. Ab initio density functional calculations have been performed for the energy and electronic structure of the fullerene-barrelene-nanotube series based on the lowest energy fullerene B₈₀. It has been shown that the energy and band gap of a barrelene are lower than the respective quantities of the corresponding fullerene and tend to the respective values for nanotubes in the infinite limit. It has been shown that there are isomers of nanotubes of the same type that are significantly different in symmetry and electronic properties: a semiconductor (C _5v symmetry) and a metal (D _5h symmetry).     

Maximum “focusing” of surface phonons

“Focusing” of surface phonons is studied in detail. Three types of surface phonon “focusing” are found. The asymptotic dependence of the amplitude u of surface wave on the distance r from a point source is obtained for every “focusing” type. The type of maximum “focusing” where $\text{u((r)～ O(r}{}^{\mathrm{<mtext>?1</mtext><mtext>4</mtext>}}\text{)}$ holds is picked out. The “focusing” type is shown to be changed as elastic anisotropy is altered.     

Carbon systems of polymerized nanotubes: Crystal and electronic structures

Molecular dynamic calculations are carried out for the (P, T) phase diagram of a covalent compound of cross-linked carbon single-wall nanotubes (SWNT) and for the structures and electronic spectra of the novel crystals of polymerized carbon nanotubes. It is shown that the transformation of covalently bonded nanotubes in a close-packed conducting structure cardinally modifies their electronic properties. The P-SWNT crystal becomes semiconducting and, upon complete transformation of sp ²-hybridized carbon atoms into sp ³-hybridized ones, it becomes an insulator.