We report on a study of the optical conductivity of single crystals of the high-Tc superconductor YBa2Cu4O8 in which superconductivity is suppressed by random substitution of Cu with Zn. The a-axis infrared spectrum, which is a direct measure of the charge dynamics in the CuO2 planes, is dominated by a bound state at ø120 cm21. This indicates that the low-energy electronic states are on the ver...

A tight-binding (TB) hamiltonian for calcium is built with a high precision parametrization technique based on density functional calculations of the energy bands and the total energy at various lattice volumes. The new set of TB parameters is appropriate to study phenomena under pressures as high as 20 GPa. Speci®cally, both the metal to nonmetal transition at 4 GPa and the structural transiti...

The type of prosthetic restoration used in implant rehabilitation greatly contributes to the recovery of masticatory function as well as quality of life in patients. Frameworks for implant-supported prostheses are typically made by casting metal or milling either titanium or zirconia. Recently, nonmetal, polymer-type materials were suggested as framework materials. Polyetherketoneketone (PEKK),...

Abstract We employ quantum molecular dynamic simulations to investigate the behavior of benzene under shock conditions. The principal Hugoniot derived from the equation of state is determined. We compare our firs-principles results with available experimental data and provide predictions of chemical reactions for shocked benzene. The decomposition of benzene is found under the pressure of 11 GP...

We have measured the 1/f noise through the metal–nonmetal transition in carbon black/polymer composites as a function of temperature and doping. At the electronic transition, the resistivity power spectrum Sr varies as Sr;r , with Q52.77, in agreement with classical three-dimensional percolation. At lower temperatures, a crossover to tunneling-dominated transport occurs with Sr ;ln Sr /r . Our ...

A first-principles self-consistent (non-muffin-tin) band-structure calculations on 1T-VSe, is used to analyze some of the transport and optical properties. The material appears to be metallic with characteristic overlaps between the metal d-based and nonmetal p-based bands. These overlaps are found to be sensitively modulated both by the change of the (anomalously high) c/a ratio and by the san...

This paper considers the Global Thermodynamic Potential (GTP) indicator to perform a unified assessment of greenhouse gas (GHG) emissions, and to systematically reveal the emission embodiment in the production, consumption, and international trade of the Chinese economy in 2007 as the most recent year available with input-output table and updated inventory data. The results show that the estima...