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External Potential (external + potential)
Selected AbstractsThe Implications of Symmetry of the External Potential on Bond PathsCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2008Erick Cerpa Sixty-coordinate atom? Using a set of molecules in which the number of "bond" paths terminating at an atom is chemically meaningless (an example is shown here); the implications of symmetry of the external potential on the presence of bond paths are discussed. [source] Polyaniline Film Based Amperometric pH Sensor Using A Novel Electrochemical Measurement SystemELECTROANALYSIS, Issue 8 2009Wei Gao Abstract A polyaniline based amperometric pH sensor has been developed using a novel electrochemical measurement system. A polyaniline film (PANI) coated pencil graphite electrode (PGE) is connected in series between the working and counter electrodes of a potentiostat, and immersed in the solution together with a reference electrode. When an external potential is applied, the resulting current varies with the solution pH, which provides the basis for the amperoemtric pH sensor. Equations describing the measurement principle are presented. Based on pH dependent emeraldine salt,emeraldine base transition of PANI film, the pH sensor exhibits high stability, accuracy, selectivity, sensitivity and a short time. [source] Current imaging in quantum point contactsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006Alessandro Cresti Abstract The experimental imaging of microscopic currents in two-dimensional electron gas based systems has been recently realized exploiting an ingenious use of scanning microscope tips. By means of the Keldysh Green's function formalism in a tight-binding framework, I study the electron transport in a model quantum point contact device, obtaining detailed maps of the local current distribution. The results are then compared with those obtained by a direct simulation of the experimental process, i.e. introducing a suitable external potential to reproduce the effect of the coupled microscopic tip on the overall conductance and the electron flow. The analysis of the differences between the two calculations helps to interpret the experimental maps and sheds light on the interference effects of the tip. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Implications of Symmetry of the External Potential on Bond PathsCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2008Erick Cerpa Sixty-coordinate atom? Using a set of molecules in which the number of "bond" paths terminating at an atom is chemically meaningless (an example is shown here); the implications of symmetry of the external potential on the presence of bond paths are discussed. [source] Inverse problems in quantum chemistryINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 11 2009Jacek Karwowski Abstract Inverse problems constitute a branch of applied mathematics with well-developed methodology and formalism. A broad family of tasks met in theoretical physics, in civil and mechanical engineering, as well as in various branches of medical and biological sciences has been formulated as specific implementations of the general theory of inverse problems. In this article, it is pointed out that a number of approaches met in quantum chemistry can (and should) be classified as inverse problems. Consequently, the methodology used in these approaches may be enriched by applying ideas and theorems developed within the general field of inverse problems. Several examples, including the RKR method for the construction of potential energy curves, determining parameter values in semiempirical methods, and finding external potentials for which the pertinent Schrödinger equation is exactly solvable, are discussed in detail. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] | ||||||||||