Equation-of-motion coupled-cluster calculations of photodetachment cross sections for atomic negative ions across the periodic table

The innovative application of the ion-trap technique by Wester and coworkers has yielded definitive experimental values of photodetachment cross sections for the atomic oxygen radical anion (O$^{\bullet -}$) [Hlavenka et al., J.~Chem.~Phys. \textbf{130}, 061105 (2009)]. In the present study, equation-of-motion coupled-cluster (EOM-CC) calculations have been performed to derive theoretical values of photodetachment cross sections for the negative ions of atoms in the first two periods of the periodic table as well as of those which belong to the alkali metal and halogen groups. Two methods have been employed to derive the cross sections. One involves the Dyson orbitals obtained from EOM-CC calculations and plane wave functions for the detached electron in the transition dipole moment integrals. The other method utilizes the moment theory following EOM-CC calculations of transition dipole moments for a large number of pseudo-states. The cross sections so evaluated for O$^{\bullet -}$ match the experimental values very well. Generally good agreement has been found between the theoretical and experimental values of the cross sections for the atoms in the first two periods, while the present calculations cast some doubt on reported experimental values for some atoms beyond the second period. Substantial relativistic effects on the cross section have been observed for heavy elements in the alkali metal and halogen groups

Direction Detector on an Excitable Field: Field Computation with Coincidence Detection

Living organisms process information without any central control unit and without any ruling clock. We have been studying a novel computational strategy that uses a geometrically arranged excitable field, i.e., "field computation." As an extension of this research, in the present article we report the construction of a "direction detector" on an excitable field. Using a numerical simulation, we show that the direction of a input source signal can be detected by applying the characteristic as a "coincidence detector" embedded on an excitable field. In addition, we show that this direction detection actually works in an experiment using an excitable chemical system. These results are discussed in relation to the future development of "field computation."Comment: 6 pages, 3 figure

Cooperative standing-horizontalstanding reentrant transition for numerous solid particles under external vibration

We report the collective behavior of numerous plastic bolt-like particles exhibiting one of two distinct states, either standing stationary or horizontal accompanied by tumbling motion, when placed on a horizontal plate undergoing sinusoidal vertical vibration. Experimentally, we prepared an initial state in which all of the particles were standing except for a single particle that was placed at the center of the plate. Under continuous vertical vibration, the initially horizontal particle triggers neighboring particles to fall over into a horizontal state through tumbling-induced collision, and this effect gradually spreads to all of the particles, i.e., the number of horizontal particles is increased. Interestingly, within a certain range of vibration intensity, almost all of the horizontal particles revert back to standing in association with the formation of apparent 2D hexagonal dense-packing. Thus, phase segregation between high and low densities, or crystalline and disperse domains, of standing particles is generated as a result of the reentrant transition. The essential features of such cooperative dynamics through the reentrant transition are elucidated with a simple kinetic model. We also demonstrate that an excitable wave with the reentrant transition is observed when particles are situated in a quasi-one-dimensional confinement on a vibrating plate

Vibronic spectra of the p-benzoquinone radical anion and cation: a matrix isolation and computational study

The electronic and vibrational absorption spectra of the radical anion and cation of p-benzoquinone (PBQ) in an Ar matrix between 500 and 40 000 cm⁻¹ are presented and discussed in detail. Of particular interest is the radical cation, which shows very unusual spectroscopic features that can be understood in terms of vibronic coupling between the ground and a very low-lying excited state. The infrared spectrum of PBQ˙⁺ exhibits a very conspicuous and complicated pattern of features above 1900 cm⁻¹ that is due to this electronic transition, and offers an unusually vivid demonstration of the effects of vibronic coupling in what would usually be a relatively simple region of the electromagnetic spectrum associated only with vibrational transitions. As expected, the intensities of most of the IR transitions leading to levels that couple the ground to the very low-lying first excited state of PBQ˙⁺ increase by large factors upon ionization, due to “intensity borrowing” from the D₀ → D₁ electronic transition. A notable exception is the antisymmetric CO stretching vibration, which contributes significantly to the vibronic coupling, but has nevertheless quite small intensity in the cation spectrum. This surprising feature is rationalized on the basis of a simple perturbation analysis

APPLICATION OF EQUATION-OF-MOTION COUPLED-CLUSTER THEORY TO PHOTODETACHMENT CROSS SECTION CALCULATIONS

Author Institution: Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712Photodetachment cross sections of atomic anions have been calculated with equation-of-motion coupled-cluster (EOM-CC) theory. Two techniques have been examined. One of them treats the photodetached electron as a plane wave, and the transition moment integral is evaluated with the Dyson orbital obtained from EOMIP-CC calculations. In the other technique, the EOM-EE method is utilized to calculate the oscillator strengths for photodetachment processes within the framework of moment theory. The results of these calculations are compared with experimental results, and the pros and cons of the two techniques are discussed

42. Transportation of object by a chemical reaction(poster presentation,Soft Matter as Structured Materials)

この論文は国立情報学研究所の電子図書館事業により電子化されました。生物は等温条件下で化学エネルギーをベクトル的な仕事に直接変換しつつ運動しており、そのメカニズムは未だ明らかではない。生体内でのエネルギーの損失は非常に少なく、その機構の解明は多くの恩恵をもたらすであろう。我々は、化学反応からベクトル的な仕事を取り出すために、Belousov-Zhabotinsky(BZ)反応が引き起こす対流現象を用いて物体を一方向へ輸送する系を作り、化学-機械エネルギー変換のメカニズムについて考察した