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Periodic zero potential surface

Atoms on sites given by the list of atomic coordinates produce electrostatic potentials. By connection of points of equal potential internal surfaces are produced which reflect essential features of the crystal structure. Periodic zero potential surfaces are discussed in Ref. 63. An example of minimal surfaces is discussed in Ref. 64. [Pg.1331]

More recent attempts to interprete the cesium effects suggest models of differential geometry [99]. So-called periodic ro-potential surfaces ( POPS ) and isopotential surfaces ( TFS , tangential eM OTrface ) of the cesimn ions as templates for organic molecules are proposed. According to these model considerations, an orientation of nonpolar molecular substructures at the zero-potential surface ( POPS ) and an orientation of polar substructures at the isopotential surface ( TFS ), take place, which should favour an intramolecular... [Pg.61]

These surfaces of zero potential formed in different salts are very close to periodic minimal surfaces [9], whose mean curvature, defined as the arithmetic mean of the main curvatures, is everywhere zero (see Chapter 1) . On these minimal surfaces the Gaussian curvature is everywhere negative or... [Pg.49]

A classical molecular dynamics trajectory is run using the quantum mechanical potential surface. Annealing periodically zeroes the kinetic energy. [Pg.512]

The great advantage of Eq. (3) is that it accounts for all beams potentially arising from the lateral periodicity of the surface. Intensities are undetermined by the equations. These might be always zero because of exclusions due to the structure factor of the unit mesh of the net, just as in three-dimensional diffraction (e.g., the beams for which h- -k... [Pg.171]

The most celebrated problem in celestial mechanics is the so-called three-body problem. First elucidated by Lagrange, this problem focuses on the determination of the allowed class of periodic motions for a massless particle orbiting a binary system. In this case, the motion is determined by the gravitational and centrifugal accelerations and also the Coriolis force. A closed form analytic solution is possible in only one case, that of equal masses in a circular orbit. This so-caUed restricted three-body problem can be specified by the curves of constant potential, also called the zero velocity surfaces. Consider a binary with a coplanar orbit for the third mass. In this case, a local coordinate system (C, r]) is defined as centered at (a, 1 — a) so that the equations of motion are... [Pg.23]

Almost all kinetic investigations on azo coupling reactions have been made using spectrophotometric methods in very dilute solutions. Uelich et al. (1990) introduced the method of direct injective enthalpimetry for such kinetic measurements. This method is based on the analysis of the zero-current potential-time curves obtained by the use of a gold indicator electrode with a surface which is periodically restored (Dlask, 1984). The method can be used for reactions in high (industrial) concentrations. [Pg.354]

Taylor et al. conducted DFT simulations using a periodic model of the interface between water and various metal surfaces with an index of (1 1 l).102 The chemistry of water at these charged interfaces was investigated and the parameters relevant to the macroscopic behavior of the interface, such as the capacitance and the potential of zero charge (PZC), were evaluated. They also examined the influence of co-adsorbed CO upon the equilibrium potential for the activation of water on Pt(l 1 1). They found that for copper and platinum there was a potential window over which water is inert. However, on Ni(l 1 1) surface water was always found in some dissociated form (i.e., adsorbed OH or H ). The relaxation of water... [Pg.357]

The DME presents special features derived from its homogeneous and isotropic drops, small size, and periodical renewed surface so that the current on each drop rises from zero to its maximum value toward the end of the drop life. Moreover, it is well known that mercury has the highest overpotential for hydrogen evolution, which enables polarization of the electrode to very negative potentials. [Pg.96]

The periodicity of the cosine functions creates the multiple potential energy wells that are required. In both CHARMM and MM3, the expansions may include multiple terms. However, the parameter sets for CHARMM generally use just a single term, such as a threefold torsional potential for rotation about a single bond. Although MM3 uses three different periodicities to describe torsional potential energy surfaces, in many cases (e.g., H—C—C—H) one or two of these terms are small or zero. [Pg.87]


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