Titanium-Oxygen Bond Length -Bond Valence Relationship

A bond length–bond valence correlation is a simple method of checking and evaluating molecular structures and is of great interest in chemistry, biology, geology, and material science. Recently, we used quantum-mechanical arguments to derive Pauling’s bond length-valence relationship and to define the adjustable fitting parameter b in terms of atomic-orbital exponents. Improved orbital exponents were generated for elements 1-103 using published atomic radii and single-bond covalent radii as well as a continuous function for effective principal quantum number. In this study, we use orbital exponents for titanium (Ti) and oxygen (O) to generate a bond length-valence relationship for Ti-O bonds. Recent crystallographic Ti-O bond lengths from 32 environments were collected and converted to Ti-O bond valences to check the reliability of the bond length-valence relationship where Ro was found (bond length of unit valence). This relationship is expected to apply to any Ti-O bond regardless of environment, physical state, or oxidation number

Gapless finite-TT theory of collective modes of a trapped gas

We present predictions for the frequencies of collective modes of trapped Bose-condensed $^{87}$Rb atoms at finite temperature. Our treatment includes a self-consistent treatment of the mean-field from finite-$T$ excitations and the anomolous average. This is the first gapless calculation of this type for a trapped Bose-Einstein condensed gas. The corrections quantitatively account for the downward shift in the $m=2$ excitation frequencies observed in recent experiments as the critical temperature is approached.Comment: 4 pages Latex and 2 postscript figure

Internal Vortex Structure of a Trapped Spinor Bose-Einstein Condensate

The internal vortex structure of a trapped spin-1 Bose-Einstein condensate is investigated. It is shown that it has a variety of configurations depending on, in particular, the ratio of the relevant scattering lengths and the total magnetization.Comment: replacement; minor grammatical corrections but with additional figure

PUPHS2D 2.0 User\u27s Manual

The Purdue University Program for Heterostructure Simulation in Two Dimensions (PUPHS2D) solves Poisson\u27s equation and the electron and hole continuity equations within a two-dimensional heterostructure device. The program will compute the electrostatic potential, electron and hole densities, recombination rate, and other quantities of interest as a function of applied bias. Like its predecessor, version 2.0 allows extensive analysis of solar cells, including computation of the current-voltage characteristics of two-terminal devices, solar cell parameters, quantum efficiency, and current versus solar intensity. Extensions to version 2.Q include transient analysis and bipolar transistor capability. The heterojunction bipolar transistor routines allow computation of dc currents as a function of applied bias, as well as quasi-static evaluation of the high-frequency behavior. A simplified energy balance equation has been added in the interest of more accurately computing high-field characteristics, and should be viewed as a preliminary step toward this goal. PUPHS2D stands as an accurate model for computing low-field device characteristics and recombinative losses. While PUPHS2D was written for the ternary AlxGai1-xAs, all material specific parameters are contained within a single subroutine (BANDX), except for absorption coefficient and carrier mobilities which are computed in subroutines ALGABS and SETMOB, respectively. Material-specific parameters used for the energy balance equation are found in subroutines INITMU and INITAU. The program may be readily modified to analyze other semiconductors. For a more thorough discussion of the theoretical basis and numerical implementation of PUPHS2D, the user is directed to the references. Materials parameters are described in reference [I]. Various phases of the development of PUPHS2D have been supported by the Semiconductor Research Corporation, Sandia National Laboratories/ the Eastman Kodak Company, and by Research Triangle Institute

A review of alternatives for local government finance

Members of the present Government, including Mrs Thatcher, have in the past expressed their determination to scrap the present system of local rates. This determination appeared to be strengthened earlier in the year by the political storm that blew up over the rates revaluation in Scotland. Revaluation in Scotland had already been delayed two years beyond the normal statutory 5-year period and the delay only served to make an even larger jump in rateable values inevitable. The storm was the greater because the last revaluation in England and Wales was in 1973. This economic perspective reviews the present rating system and considers the alternatives which have been proposed by Government

Parametrically controlling solitary wave dynamics in modified Kortweg-de Vries equation

We demonstrate the control of solitary wave dynamics of modified Kortweg-de Vries (MKdV) equation through the temporal variations of the distributed coefficients. This is explicated through exact cnoidal wave and localized soliton solutions of the MKdV equation with variable coefficients. The solitons can be accelerated and their propagation can be manipulated by suitable variations of the above parameters. In sharp contrast with nonlinear Schr\"{o}dinger equation, the soliton amplitude and widths are time independent.Comment: 4 pages, 5 eps figure

Universal simulation of Hamiltonian dynamics for qudits

What interactions are sufficient to simulate arbitrary quantum dynamics in a composite quantum system? Dodd et al. (quant-ph/0106064) provided a partial solution to this problem in the form of an efficient algorithm to simulate any desired two-body Hamiltonian evolution using any fixed two-body entangling N-qubit Hamiltonian, and local unitaries. We extend this result to the case where the component systems have D dimensions. As a consequence we explain how universal quantum computation can be performed with any fixed two-body entangling N-qudit Hamiltonian, and local unitaries.Comment: 13 pages, an error in the "Pauli-Euclid-Gottesman Lemma" fixed, main results unchange