Correlation energy in a transition metal

Correlation energies of the nondegenerate and the degenerate Hubbard models are calculated with second order perturbation theory and with a variational local ansatz. By comparing these results, we discover an overestimate of the correlation energy in the perturbation treatment. The overestimate is due to the independent treatment of electron correlations in different orbital states. We also demonstrate the qualitative difference in electron correlation between the two models.     

α-zirconium hydrogenphosphate,monohydrate. preparation,chemical properties and ac conductivity

The preparation of zirconium hydrogenphosphate, monohydrate (αZrP) was performed by two methods giving materials with slightly different properties. It is shown that the particle size of αZrP depend upon the method of preparation and the washing procedures, and that the ac conductivity decreases with increasing particle size (5 x 10^-6 to 5 x 10^-5 Ω^-1 cm^-1 at 20°C). The activation energy has been determined to 0.25 eV/mol (between 20°C and about 100°C) independent of the particle size, showing αZrP to be a surface ion conductor.     

Kinetics and mechanism for the oxidation of 1,1,1-trichloroethane

The reaction mechanisms for oxidation of CH₃CCl₂ and CCl₃CH₂ radicals, formed in the atmospheric degradation of CH₃CCl₃ have been elucidated. The primary oxidation products from these radicals are CH₃CClO and CCl₃CHO, respectively. Absolute rate constants for the reaction of hydroxyl radicals with CH₃CCl₃ have been measured in 1 atm of Argon at 359, 376, and 402 K using pulse radiolysis combined with UV kinetic spectroscopy giving ??(OH + CH₃CCl₃) = (5.4 ± 3) 10^?12 exp(?3570 ± 890/RT) cm³ molecule^?1 s^?1. A value of this rate constant of 1.3 × 10^?14 cm³ molecule^?1 s^?1 at 298 K was calculated using this Arrhenius expression. A relative rate technique was utilized to provide rate data for the OH + CH₃ CCl₃ reaction as well as the reaction of OH with the primary oxidation products. Values of the relative rate constants at 298 K are: ??(OH + CH₃CCl₃) = (1.09 ± 0.35) × 10^?14, ??(OH + CH₃CClO) = (0.91 ± 0.32) × 10^?14, ??(OH + CCl₃CHO) = (178 ± 31) × 10^?14, ??(OH + CCl₂O) < 0.1 × 10^?14; all in units of cm³ molecule^?1 s^?1. The effect of chlorine substitution on the reactivity of organic compounds towards OH radicals is discussed.     

Prosessdataenhet for GIER

The paper describes a new analog-to-digital linkage system for the GIER digital computer, intended for real time data processing and control. The system comprises a peripheral unit with several analog and digital input/output channels, and an automatic program interrupt feature. The development work has been carried out as a joint effort by Regnecentralen, the Danish Institute for Computing Machinery and the Division of Automatic Control at the Technical University of Norway.     

Collapse of cylindrical, elastic tubes under combined bending, pressure and axial loads

A study of the non-linear pre-buckling state and the bifurcation and initial post-buckling behaviour of infinitely long, cylindrical, elastic tubes subjected to bending, pressure and axial loads is presented. The collapse behaviour is analysed by determining both the limit load and the possibility and significance of axial wrinkling of the compressed region of the shell prior to the limit load.     

Bipolaron stability

The bipolaron stability is investigated in a finite system for which analytical solutions are derived. Whenever the bipolaron singlet can be well defined and is deeply bound, the bipolaron triplet is also bound. The presence of the bipolaron triplet between the bipolaron singlet and the free polaron band plays a very important role in determining the thermodynamic properties of the bipolaron.