The high-pressure behavior of rocksalt-structured FeO has been investigated using the LDA + U method, a first-principles computational technique that allows treatment of correlated electrons with strong localized repulsions. Within the local density approximation (LDA) FeO is predicted to be a metal, but with LDA + U, an insulating state is obtained at zero pressure. Electronic and magnetic beh...

Using DFT methods we have studied structure, equation of state, and phase behavior of BaTiO3. We have identified the pressure induced phase transformations from the rhombohedral to orthorhombic structure at ca. 5 GPa and from tetragonal phase to cubic phase at ca. 7.5 GPa. INTRODUCTION BaTiO3 is an important example perovskite structured ceramic displaying ferroelectric property. At high temper...

A new ultra-hard rhombohedral carbon rh-C4 (or hexagonal h-C12) is reported as derived from 3R graphite through crystal chemistry construction and ground state energy within the density functional theory. An extended three-dimensional network of h-C12 formed C4 tetrahedra alike in h-C4 lonsdaleite (hexagonal diamond). The electronic band structure characteristic insulator with Egap = 4 eV simil...

We have synthesized novel crystalline ropes of "polygonized" single-wall carbon nanotubes (SWCNTs). The tubes exhibit rounded-hexagonal cross sections in contrast to the earlier observations of nearly circular tubes. To investigate the structural characteristics of the lattice of SWCNTs we have performed extensive molecular-dynamics simulations. We find several metastable structures of the latt...

Bismuth selenide (Bi2Se3) nanostructures were synthesized via solvothermal method. The crystallinity of the as-synthesized sample has been analyzed by X-ray diffraction, which shows the formation of rhombohedral Bi2Se3. Electron microscopy examination indicates that the Bi2Se3 nanoparticles have hexagonal flake-like shape. The effect of the synthesis temperature on the morphology of the Bi2Se3 ...

Kepler’s Conjecture, recently proved by T. Hales, states that the densest packing of spheres in 3-space has spheres centered along the face-centered cubic (fcc) lattice. A lattice is a free Z-module formed by taking the span of a collection of linearly independent vectors in R over the integers. The two-dimensional analogue of Kepler’s Conjecture, proved by L. F. Toth in 1940, states that the d...

We find the generating function of self-avoiding walks (SAWs) and trails on a semi-regular lattice called the 3.122 lattice in terms of the generating functions of simple graphs, such as SAWs, self-avoiding polygons and tadpole graphs on the hexagonal lattice. Since the growth constant for these graphs is known on the hexagonal lattice we can find the growth constant for both walks and trails o...

A single phased Y-type hexagonal ferrite Sr2Co1.7Mg0.3Fe11.2Sn0.4Zn0.4O22 was synthesized by the sol–gel auto combustion method. Structural and magnetic properties of this composition of Y-type hexagonal ferrite have been investigated. The X-ray diffraction (XRD) patterns confirm single phase Y-type hexagonal ferrite and various parameters such as lattice constants and cell volume have been cal...

We find the generating function of self-avoiding walks and trails on a semi-regular lattice called the 3.122 lattice in terms of the generating functions of simple graphs, such as self-avoiding walks, polygons and tadpole graphs on the hexagonal lattice. Since the growth constant for these graphs is known on the hexagonal lattice we can find the growth constant for both walks and trails on the ...