The variable core approach in the SCF MO calculation of heteroatomic systems

A charge density dependency of the core energy in the SCF MO theory has been derived. According to the present theory, the core energy, U , associated with the ^th 2p-AO should linearly vary with the charge density, q . SCF MO calculations based on this variable core approach have been carried out for some N-heterocycles, aromatic amino derivatives, and protonated pyridine. The results for the electronic spectra of neutral molecules are almost the same as those based on the conventional SCF MO method. However, the calculated charge distributions are somewhat different. An interesting result is that the present theory calculates a slightly negative net charge at the meta positions in aniline.

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Zusammenfassung Es wird eine SCF-MO-Methode entwickelt, in der das dem 2p -AO entsprechende Rumpfintegral U linear von der Ladungszahl q abhängt. Es werden einige N-Heterocyclen, aromatische Aminoderivate und das Pyridinium-Ion durchgerechnet. Die Elektronenspektren der neutralen Moleküle ergeben sich wie mit der üblichen Methode; die Ladungsverteilung ist jedoch etwas verändert. Beispielsweise führt die neue Methode zu einer geringen negativen Überschußladung in der Metaposition des Anilins.

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Résumé On a établi une relation de dépendance entre l'énergie de coeur et la densité de charge en méthode SCF MO. Salon la théorie ci-dessous l'énergie de coeur U , associée à la ième orbitale atomique 2, devrait varier linéairement avec la densité de charge q . Des calculs SCF MO basés sur cette hypothèse de coeur variable ont été effectués pour quelques N-hétérocycles, dérivés aminés aromatiques et pour la pyridine protonisée. Les résultats concernant les spectres électroniques des molécules neutres sont pratiquement identiques à ceux obtenus par la méthode SCF MO conventionelle. Cependant les distributions de charges obtenues sont quelque peu différentes. Un résultat intéressant de cette théorie est la faible charge nette négative en position méta dans l'aniline.

     

An application of RPA theory to conjugated systems in the excited states

RPA theory has been applied to the calculations of the electronic spectra of some conjugated systems, considering only -electrons explicitly. Electron repulsion integrals have been calculated using Slater AO's with appropriate orbital exponents. The present calculation shows that the correlation effect between -electrons is rather small for the lowest — ^* transitions. Good results have been obtained, when we calculate the electron repulsion integrals using orbital exponents evaluated by Slater rule. Effective electron interaction in the excited states has been discussed, using the calculated results. The calculated oscillator strengths were considerably improved by RPA,

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Zusammenfassung Die RPA wurde auf die Berechnung der UV-Spektren des -Elektronensystems konjugierter Moleküle angewendet, wobei die Coulombintegrale für Slaterorbitate mit Exponenten gemäß der Slaterregeln ermittelt wurden. Es zeigt sich, daß die Korrelationseffekte für die tieferen Übergänge ziemlich gering sind und daß sich insbesondere die Oszillatorenstärken sehr gut ergeben. Schließlich wurden eine effektive Elektronenwechselwirkung in angeregten Zuständen diskutiert.

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Résumé La théorie RPA fondée sur l'équation du mouvement a été appliquée à des calculs de la structure électronique et des spectres de systèmes conjugués en ne considérant explicitement que les électrons . Les intégrales de répulsion électronique ont été calculées en utilisant des OA de Slater avec des exposants orbitaux appropriés. Nos calculs montrent que les effets de corrélation entre électrons sont plutôt faibles pour les plus basses transitions — ^*. De bons résultats ont été obtenus en calculant les intégrales de répulsion électronique en utilisant les exposants orbitaux évalués par la règle de Slater. L'interaction électronique effective dans les états excités est discutée sur la base des résultats obtenus.

     

An Improvement in the calculation of electron repulsion integrals in Pariser-Parr-Pople theory—Electron interactions in molecules

An improvement in the calculation of electron repulsion integrals in Pariser-Parr-Pople theory has been made, considering the following two characteristic features associated with electron interactions in molecules; Firstly, a given -electron moves in the sea of electron clouds consisted of -electrons and other -electrons, which forms a polarizable dielectric medium. Secondly, in alternant hydrocarbons, -electrons will be alternatively distributed to the upper and lower sides of molecular plane. The present idea is applied to SCF MO calculations of simple hydrocarbons. Calculated results for singlet and triplet transitions energies, and first ionization potentials are in good agreement with experimental data.

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Zusammenfassung Bei der Berechnung der Elektronenwechselwirkungsintegrale im Rahmen der PPP-Theorie wird eine Verbesserung angegeben, die folgende Charakteristika betrifft: 1. Ein gegebenes -Elektron bewegt sich im Feld der übrigen - und -Elektronen, die ein polarisierbares elektrisches Medium bilden; 2. in alternierenden Kohlenwasserstoffen sind die -Elektronen abwechselnd auf der Ober- und Unterseite der Molekülebene verteilt. Diese Idee wird auf SCF MO Rechnungen von einfachen Kohlenwasserstoffen angewandt. Die Ergebnisse von Singulett- und Triplettübergangsenergien und Ionisierungspotentialen stimmen mit den experimentellen Daten gut überein.

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Résumé On a amélioré le calcul des intégrales de répulsion électronique dans la théorie de Pariser-Parr-Pople en prenant en considération les deux aspects caractéristiques suivant de l'interaction électronique dans les molécules. Premièrement, un électron donné se déplace dans la mer des nuages électroniques des électrons et des autres électrons , qui forme un milieu diélectrique polarisable. Deuxièmement, dans les hydrocarbures alternants, les électrons seront alternativement distribués sur les cÔtés supérieurs et inférieurs du plan moléculaire. Cette idée est appliquée à des calculs SCF MO d'hydrocarbures simples. Les résultats des calculs pour les énergies de transition singulet et triplet et pour les premiers potentiels d'ionisation sont en bon accord avec les donées expérimentales.

     

Photocurrent response after enzymatic treatment of DNA duplexes immobilized on gold electrodes: electrochemical discrimination of 5-methylcytosine modification in DNA

We demonstrate a photoelectrochemical approach to the detection of the methylation status of cytosine bases in DNA. We prepared anthraquinone (AQ) photosensitizer-tethered oligodeoxynucleotide (ODN) duplexes bearing 5-methylcytosine (mC) or the corresponding cytosine (C) at a restriction site of the ODN strand immobilized on gold electrodes, and measured their photocurrent responses arising from hole transport after enzymatic digestion. Treatment with HapII or HhaI of the duplexes bearing normal C led to strand cleavage, and the photosensitizer unit was eliminated from the ODN strand immobilized on the gold electrode, exclusively reducing the photocurrent density. With a similar treatment, the duplexes bearing mC showed higher photocurrent responses arising from hole transport through the duplex. This significant difference in the photocurrent response between mC and normal C residues in DNA on the gold electrodes is potentially applicable to the detection of mC modification in DNA.     

InxGa1−xAs/GaAs quantum wire structures grown on GaAs (100) patterned substrates with [001] ridges

In_xGa_1−xAs/GaAs (x = 0.12-0.23) quantum well (QW) structures were grown by molecular beam epitaxy (MBE) on [001] ridges with various widths (1.1-12 μm) of patterned GaAs (100) substrate. The smallest lateral width of the InGaAs/GaAs quantum wire (QWR) structures was estimated to be about 0.1 μm by high-resolution scanning electron microscope (SEM). The In contents of the grown InGaAs/GaAs QWs on the ridges were studied as a function of ridge top width (ridge width of the MBE grown layer) by cathodoluminescence (CL) measurements at 78 K. Compared to the InGaAs QW grown on a flat substrate, the In content of the InGaAs/GaAs QW on the ridge increases from 0.22 to 0.23 when the ridge top width decreases to about 2.9 μm, but it decreases steeply from 0.23 down to 0.12 with a further decrease of the ridge width from 2.9 to 0.05 μm. A simulation of MBE growth of InGaAs on the [001] ridges shows that this reduced In content for narrow ridges is due to a large migration of Ga atoms to the (100) ridge top region from {110} side facets.     

Mössbauer study of a novel binuclear Fe(II/III) delocalized-valence compound

In this paper, we briefly summarize the main conclusions of the Mössbauer analysis of [L₂Fe₂(-OH)₃] (ClO₄)₂·2CH₃OH·2H₂O with L=N,N',N"-trimethyl-1,4,7-triazacyclononane, a novel dimeric iron compound, which possesses a central exchange-coupled delocalized-valence Fe(II/III) unit. The complete delocalization of the excess electron in the dimeric iron center is concluded from the indistinguishability of the two iron sites in Mössbauer spectroscopy. The magnetic Mössbauer spectra imply a system spinS _t=9/2 for the dimer in its ground state. The values for hyperfine and spin-Hamiltonian parameters, obtained from simulations of the Mössbauer spectra, are =0.74 mms^–1, E _Q=–2.14 mms^–1,A =–10.6 T,A =–13.5 T andD=1.8 cm^–1. The system spinS _t=9/2 is interpreted to be a consequence of double-exchange coupling.     

Some fractional differintegral equations

Recently, Nishimoto [J. College. Engrg. Nihon Univ. Ser. B24 (1983), 7–13] studied a certain fractional integral equation and a system of simultaneous differintegral equations, each of order $\text{1}\text{2}$. Motivated by Nishimoto's work, Owa and Nishimoto [J. College Engrg. Nihon Univ. Ser. B24 (1983), 67–72] considered a general fractional differintegral equation. The object of the present paper is to investigate some interesting properties of functions which satisfy the general fractional differintegral equation solved by Owa and Nishimoto.     

TiO2-based superhydrophobic-superhydrophilic patterns: Fabrication via an ink-jet technique and application in offset printing

A superhydrophobic-superhydrophilic pattern was prepared on an anodized Al plate by a new fabrication process. The process consists of five key steps: (1) TiO₂ coating of the plate, (2) surface modification with self-assembled monolayers (SAMs), (3) formation of aqueous UV light-resistant ink patterns by an ink-jet technique, (4) photocatalytic decomposition of SAMs and surface conversion to the superhydrophilic state and (5) removal of the aqueous ink patterns by water washing. It is particularly noteworthy that the wettability pattern can be quickly formed on the plate, without the use of a photomask. The fabricated superhydrophobic-superhydrophilic pattern is shown to be applicable to offset printing.     

WhozThat? evolving an ecosystem for context-aware mobile social networks

One of the most compelling social questions, which until now was left unanswered by current technology, is "Who's that?" This question is usually asked about a new unfamiliar person in a social setting who piques your curiosity. This article presents WhozThat, a system that ties together online social networks with mobile smart- phones to answer this common and essential social question. WhozThat builds an infrastructure that shares social networking IDs locally, using wireless technology, while also leveraging a wireless connection to the Internet's social networks to bind identity with location. In addition, WhozThat offers an entire ecosystem on which increasingly complex context-aware applications can be built; that is, once the environment knows who one is, the environment can adapt its content based on the individual's identity or even the collective tastes of a local group. We describe a prototype of the basic WhozThat system and also describe a more advanced service we built, a context-aware music player. We also discuss security and privacy issues introduced by mobile social networks.