Observation of excitation in asymmetric flux qubits coupled inductively

We measured magnetic flux produced by coupled flux qubits with a switching current measurement of a DC-SQUID. Both the circulating currents and the SQUID–qubit coupling were designed to be asymmetric. The experimental result exhibits a broad peak and dip, and does not agree with the thermally averaged magnetic flux calculated with the two qubit Hamiltonian. This disagreement can be explained in terms of nonthermal excitation of the coupled qubits, which is probably caused by the microwaves generated by the DC-SQUID in the voltage state.     

Phase transition in the family LaxBi4−xTi3O12: In relation to lattice symmetry and distortion

The ferroelectric phase transition in the family La_xBi_4?xTi₃O₁₂ was investigated by X-ray diffractometry and differential scanning calorimetry. The crystal symmetry is orthorhombic in the range of 1 > x ≥ 0 and tetragonal in x ? 1. It was found that the shift of the phase-transition temperature is closely related to crystallographic symmetry and lattice distortion. (1) As the value of x increases, the ratio of lattice parameters, $\text{a}\text{b}$, decreases toward 1. (2) In the range of 1 > x ≥ 0, the lattice distortion increases with increasing x; just before x exceeds about 1, the distortion reaches a maximum. (3) As x exceeds about 1, the distortion decreases distinctively. (4) In the orthorhombic region, the phase-transition temperature decreases with increasing x. (5) In the tetragonal region, the transition does not occur. (6) The relation of transition temperature T_c to x is represented by a nonlinear function.     

New implementation of second-order Møller-Plesset perturbation theory with an analytic Slater-type geminal

The author introduces a new method for the exchange commutator integrals in explicitly correlated M?ller-Plesset second order perturbation theory. The method is well suited with an analytic Slater-type geminal correlation factor. He also explains the scheme for auxiliary integrals needed for the correlation factor. Based on different Ans?tze, he analyzes the performance of the method on correlation energies and reaction enthalpies in detail.     

Radical-scavenging activity of natural methoxyphenols vs. synthetic ones using the induction period method

The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X = NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH3)3, C6H5) and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were investigated using differential scanning calorimetry (DSC) by measuring their anti-1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activity and the induction period for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO). 2-Allyl-4-methoxyphenol and 2,4-dimethoxy-phenol scavenged not only oxygen-centered radicals (PhCOO*) derived from BPO, but also carbon-centered radicals (R*) derived from the AIBN and DPPH radical much more efficiently, in comparison with eugenol and isoeugenol. 2-Allyl-4-methoxyphenol may be useful for its lower prooxidative activity.     

Reduction behavior of Ru/CeO2 catalysts and their activity for wet oxidation

Three kinds of Ru/CeO₂ catalysts were prepared. The mobility of the oxygen on Ru and their catalytic activity in the wet oxidation of acetic acid was investigated. Ru was present in the form of RuO₂, and TPR experiment showed that the reaction, RuO₂ + 2H₂ Ru + 2H₂O, took place in different temperature ranges depending upon the kind of the catalysts. The catalyst with easily reducible oxygen on Ru had high activity in wet oxidation, and the importance of the release of oxygen from Ru to the reactant was suggested.     

MPI/OpenMP hybrid parallel implementation of second-order M?ller�CPlesset perturbation theory using numerical quadratures

An algorithm for massively parallel computers is developed for energy calculations of second-order M?ller?CPlesset (MP2) perturbation theory with numerical quadratures. Message Passing Interface (MPI) and Open Multi-Processing (OpenMP) technologies are utilized for inter-node and intra-node parallelization, respectively. Computational tasks and intermediates are distributed across nodes by dividing quadrature points, and the distributed data are stored in memory. Benchmark calculations were performed on 256?C8,192 CPU cores, and we observed the speed-ups 4,534?C6,266 for 8,192 cores. A large calculation for fullerene (C₆₀) with aug-cc-pCVTZ (3,540 basis functions) was completed in ca. 4.8?h on 8,192 cores without invoking molecular symmetry.     

Stein’s method for invariant measures of diffusions via Malliavin calculus

Given a random variable F$F$ regular enough in the sense of the Malliavin calculus, we are able to measure the distance between its law and any probability measure with a density function which is continuous, bounded, strictly positive on an interval in the real line and admits finite variance. The bounds are given in terms of the Malliavin derivative of F$F$. Our approach is based on the theory of Itô diffusions and the stochastic calculus of variations. Several examples are considered in order to illustrate our general results.     

Odd-frequency superconductivity on the Hubbard model using the FLEX approximation

It is an important issue to clarify whether the odd-frequency superconducting state can be derived from microscopic Hamiltonian or not, where gap function has an odd-parity in frequency. We study the instability of following four superconducting states: (1) even-frequency spin-singlet, (2) even-frequency spin-triplet, (3) odd-frequency spin-singlet and (4) odd-frequency spin-triplet. By using the fluctuation exchange (FLEX) approximation on a triangular and square lattice, we find that the odd-frequency spin-triplet pairing can become dominant at a certain region where the suppression of the antiferromagnetic fluctuation due to a geometric frustration becomes prominent.     

Efficient synthesis of trans- or cis-4(5)-(5-aminomethyltetrahydrofuran-2-yl)imidazoles via diazafulvene intermediates: synthetic approach toward human histamine H4)-ligands

(+)-4(5)-[(2R,5R)-5-aminomethyltetrahydrofuran-2-yl]imidazole [(+)-1, imifuramine] and its 2R,5S-stereoisomer (+)-2 were expected as base compounds to develop selective human histamine H4-receptor ligands. The improved synthesis of (+)-1 was done via cyclization of a diazafulvene intermediate generated by Bu3P/N,N,N',N'-tetramethylazodicarboxamide (TMAD) treatment of a diol 17ab bearing an unsubstituted imidazole moiety in good yields. This methodology also afforded an alternative synthetic route to trans- and cis-ethyl 4(5)-(5-hydroxymethyltetrahydrofuran-2-yl)imidazole carboxylates (5 and 6), reported previously. Also, 4(5)-[(2R,5S)-5-aminomethyltetrahydrofuran-2-yl]imidazole (+)-2 was synthesized from ethyl 4(5)-(2-deoxy-beta-D-ribofuranosyl)imidazole-1-carboxylate (35) via the four steps involving deoxygenation.     

Three-center expansion of electron repulsion integrals with linear combination of atomic electron distributions

A new systematic way of constructing auxiliary basis functions for approximating the evaluation of electron repulsion integrals is proposed and applied to SCF and MCSCF wavefunction calculations. In the approximation, the one-electron density is expanded in terms of a linear combination of atomic electron distributions (LCAD), and the four-center two-electron repulsion integrals are reduced to the three- and two-center quantities. This results in a high-accuracy approximation as well as a large reduction in disk storage and input/output requirement, proportional to N³ rather than N⁴, N being the number of basis functions. Numerical results indicate that the error from the present approximation decreases as the size of molecular basis functions increases and that the LCAD version of MCSCF calculations requires only a fractional amount of the CPU time required in the conventional procedure without loss of accuracy.