Structural basis for the conducting interface between LaAlO3 and SrTiO3

The complete atomic structure of a five-monolayer film of LaAlO3 on SrTiO3 has been determined for the first time by surface x-ray diffraction in conjunction with the coherent Bragg rod analysis phase-retrieval method and further structural refinement. Cationic mixing at the interface results in dilatory distortions and the formation of metallic La(1-x)SrxTiO3. By invoking electrostatic potential minimization, the ratio of Ti{4+}/Ti{3+} across the interface was determined, from which the lattice dilation could be quantitatively explained using ionic radii considerations. The correctness of this model is supported by density functional theory calculations. Thus, the formation of a quasi-two-dimensional electron gas in this system is explained, based on structural considerations.     

Elastic proton-proton scattering: Excitation functions from 0.45 to 2.5 GeV

Excitation functions of the differential cross sections dσ/dgw, analyzing powers A_N and spin correlation parameters A_NN, A_SS and A_SL have been measured with internal targets at the Cooler Synchrotron COSY. Data were taken continously during the acceleration and deceleration of the internal beam for kinetic energies between 450 and 2500 MeV and scattering angles 30° σ_cm 90°. Details of the experimental method are presented. The results provide excitation functions and angular distributions of high precision and internal consistency. No evidence for narrow structures are found. Upper limits on the coupling of narrow resonances to elastic scattering in the mass range √s = 2.2…2.8 GeV are deduced. The data have significant impact on phase shift solutions.     

Phase factors in bases for solutions of time-dependent schrödinger equations

The time-dependent Schrödinger equation is formulated within a model space by means of a finite set of coupled, linear differential equations. The basis is spanned by a set of orthogonal and well-defined many body wave-functions, which are solutions of a model Hamiltonian in a “moving frame”. As a by-product one is able to separate approximatively collective potential, collective kinetic, and intrinsic excitation energy for arbitrary collective motion. For the two types of motion discussed in greater details (i.e. center of mass and quadrupole motion), the expressions for the collective kinetic energy approach their correct asymptotic values.     

Quantizing QED2 on the light-cone

The method of discretized light-cone quantization (DLCQ) is applied to quantum electrodynamics in one space and one time dimension (QED₂) with different initial conditions. This leads to different representations of the operators of the constants of motion. Within the fermion-antifermion approximation we perform analytically the transition to the continuum limit and show that the discrete massive and massless representations are equivalent. We compare a semiclassical calculation of the number of bound states with the results obtained in the continuum limit. Furthermore a discrete bosonized version of QED₂ is discussed.     

A microscopic,but not self-consistent approach to nuclear binding and deformation energies

Using various versions of the Skyrme force and Negele's interaction, we calculate deformation energies of nuclei by evaluating the expectation value of the many-body Hamiltonian in wave functions taken to be antisymmetrized products of single-particle functions. These single-particle functions are eigenfunctions of a phenomenological potential, here taken to be a deformed Woods-Saxon well. The method can be thought of as an extension of the Strutinsky shell-correction method, to make the connection with the two-body interaction. The method employed here is checked by comparison with Hartree-Fock (HF) results; our method is, however, much faster than the HF method, and, therefore, suitable for a wide range of problems where one tests the sensitivity of results to changes in the two-body interaction. A fairly good agreement with the HF method is obtained for ground-state energies, radii and deformations, as well as for deformations of shape isomers. The main discrepancy is that our energies tend to increase slightly too rapidly with deformation, indicating that we may not have chosen the best phenomenological well. Two-dimensional energy surfaces, which agree quite well with those from the Strutinsky method, are found for ²⁴⁰Pu.     

Redox-induced coordination isomerization of a phosphoniobenzophospholide

1-Triphenylphosphoniobenzo[c]phospholide 1 reacts with [M(CO)(5)Br] (M = Mn, Re) and [Mn(CO)(3)(naphthalene)][BF(4)] to give complexes cis-[M(CO)(4)(1)Br] (5 a,b) and [Mn(CO)(3)(1)][BF(4)] (6 a[BF(4)]), respectively, featuring eta(1)(P)- and eta(5)(pi)-coordination of the phosphole ring. The corresponding reactions with [M(2)(CO)(10)] proceed with conservation of the metal-metal bond and yield, depending on the reaction temperature, dinuclear complexes [M(2)(CO)(8)(1)] (M=Mn, 7 a) or [M(2)(CO)(6)(1)(2)] (M=Mn, Re, 8 a,b) with mu(2)-bridging eta(1)(P):eta(2)(Pdbond;C) coordination of the phosphole moiety. All complexes formed were characterized by spectroscopic data; 5 b, 6 a[BF(4)], and 8 a,b were characterized by X-ray diffraction studies as well. The structural and (31)P NMR data of the dinuclear manganese complex 8 a suggest that the interaction between the metal atoms and the eta(2)-bound Pdbond;C double bond moieties is dominated by the L-->M charge-transfer contribution; this hints at a very low back-donation ability of the central M(2)(CO)(6) fragment. Investigation of the reactions of the Mn complexes 6 a and 8 a with Mg or ferrocenium hexafluorophosphate ([Fc][PF(6)]), respectively, revealed that the chemically reversible mutual interconversion between both species was feasible. Likewise, oxidation of the rhenium complex 8 b with [Fc][PF(6)] gave spectroscopic evidence for the formation of a Re analogue of 6 a. Electrochemical studies suggested that the oxidation 8 a-->2 6 a involves two consecutive single-electron-transfer steps, the first of which is electrochemically reversible and produces a metastable radical cation that is detectable by ESR spectroscopy. The mutual interconversion between 6 a and 8 a represents the first case of a reversible coordination isomerization of a phosphaarene that is triggered by a redox process and might stimulate further studies directed at the use of dinuclear phosphaarene complexes in redox-catalysis.     

A Hartree-Fock-Roothaan analogon using the principle of variance minimization

The variance-minimizing Roothaan-like equation derived in a preceding paper [1] gives rise to a double iteration procedure. The procedure is tested by application on some simple atomic systems, using Slater-type basis functions. The integrals needed for atomic systems and Slater-type basis functions are solved.