Electrostatic potential distribution

Exposure and latent image formation. The sensitized photoreceptor is exposed to a light and dark image pattern in the light areas the surface potential of the photoconductor is reduced due to a photoconductive discharge. Since current can only flow perpendiculai to the surface, this step produces an electrostatic-potential distribution which replicates the pattern of the image. 

More complicated is the evolution of the hydrogen distribution in situations where the electrostatic potential distribution is affected not only by... 

The mechanism by which electrons interact with crystals is different from that of X-rays. X-rays detect electron density distribution in crystals, while electrons detect electrostatic potential distribution in crystals. Electron crystallography may be used for studying some special problems related to potential distribution such as the oxidation states of atoms in the crystal. 

D reconstruction can be performed by restoring the 3D Fourier space of the object from a series of 2D Fourier transforms of the projections. Then the 3D object can be reconstructed by inverse Fourier transformation of the 3D Fourier space. For crystalline objects, the Fourier transforms are discrete spots, i.e. reflections. In electron microscopy, the Fourier transform of the projection of the 3D electrostatic potential distribution inside a crystal, or crystal structure factors, can be obtained from HREM images of thin crystals. So one can obtain the 3D electrostatic potential distribution (p(r) inside a crystal from a series of projections by... 

The purpose of the present chapter is to introduce some of the basic concepts essential for understanding electrostatic and electrical double-layer pheneomena that are important in problems such as the protein/ion-exchange surface pictured above. The scope of the chapter is of course considerably limited, and we restrict it to concepts such as the nature of surface charges in simple systems, the structure of the resulting electrical double layer, the derivation of the Poisson-Boltzmann equation for electrostatic potential distribution in the double layer and some of its approximate solutions, and the electrostatic interaction forces for simple geometric situations. Nonetheless, these concepts lay the foundation on which the edifice needed for more complicated problems is built. 

Varnek, A.A. Kuznetsov, A.N. Petrukhin, O.M. Electrostatic potential distribution and extraction ability of some organophosphorus compounds. Zh. Structumoi Khim. (Russ.) 1989, 30, 44-48. 

The upper sign corresponds to a water-dielectric , and the lower one to a water-conductor type of interface. Equation (7) shows that a charge located next to a conductor will be attracted by its own image, and dielectrics in aqueous solutions will repel it. For a review of statistical-mechanical models of the double layer near a single interface we refer to [7], and here we would like only to illustrate how the image forces will alter the ion concentration and the electrostatic potential distribution next to a single wall. At a low electrolyte concentration the self-image forces will mostly dominate, and the ion-surface interaction will only be affected by the polarization due... 

In the case of metallic particles, just this second term dominates the electrostatic potential distribution in the electrolyte solution. As a good approximation in this situation the interaction at a constant electrostatic surface potential may be assumed. However, this approximation does not reflect the actual situation—this latter may slightly depart from the model regime assumed [21]. 

Automatic Search of Maximum Similarity Between Molecular Electrostatic Potential Distributions. ... 

Manaut, F., Sanz, F., Jos6, J. and Milesi, M. (1991). Automatic Search for Maximmn Similarity Between Molecular Electrostatic Potential Distributions. J.Comput.Aid.Molec.Des., 5, 371-380. 

An important reason for calculating the electrostatic potential distribution is to obtain experimentally measurable properties. In some cases the electrostatic potential or field itself is directly measurable. In these cases no further calculation is necessary to obtain the appropriate experimental quantity. Examples of applications like this include the measurement and calculation of a-helix potentials and fields (Lockhart and Kim 1993 Lockhart and Kim 1992 Sitkoff et al. 1994a), the measurment and calculation of potentials around DNA (Hecht and Honig 1995 Shin and Hubbell 1992) and at membrane surfaces (McDaniel et al. 1986). Another application is when the stabilization potential at a particular site in a protein is required. An example is the evaluation of the protein potential at the oxyanion hole in a serine protease (Soman et al. 1989). Most experimental parameters of interest, however, are obtained by combining the results of an electrostatic calculation with further theoretical analysis or calculations. 

Coming back to the case of polyoxometalates, Rohmer et al. [29] found that electronically inverse host anions are formed in solution by means of a template mechanism which tends to maximize the electrostatic potential at the place of the guest anion. These authors also provided a correlation between the topology of the host and its molecular electrostatic potential, which explains on the basis of simple geometric considerations the difference between electronically normal and electronically inverse hosts. With the aid of this correlation it can be shown that the host cage tends to adapt not only to the shape of the guest molecule, but also to its electrostatic potential distribution [29]. 

Kohonen neural networks are able to map the surface of a molecule together with its electrostatic potential distribution onto a 2D plane the Kohonen map. These maps can be compared since their size is independent of the size of the molecule s surface. The lower right images in Figure 6.38 show an example a pattern of the electrostatic potential mapped into a 2D plane as performed by a Kohonen neural network. This visual representation can be used as a descriptor in a search for compounds with similar biological activity. 

Luque FJ, Orozco M, Illas F, Rubio J. Effect of electron correlation on the electrostatic potential distribution of molecules. J Am Chem Soc 1991 113 5203-5211. 

Du Q, Arteca GA. Derivation of fused-sphere molecular surfaces from properties of the electrostatic potential distribution. J Comput Chem 1996 17 1258-1268. 

Manaut F, Sanz F, Jose J, Milesi M. Automatic search for maximum similarity between molecular electrostatic potential distributions. J Comput-Aided Mol Des 1991 5 371— 380. 

Several new possibilities have become apparent along the path of the QSM theoretical development [44], Among others, one can quote Electrostatic Potential distributions as well as eDF transformations. Thus, one can say that eDF analysis and the attached concept of Quantum Object (QO) [41,45,46] have opened the way towards an almost complete definition of the structure of QSM and their generalisations. At the end, a mathematical picture of the connection between chemical information and the idea of molecule emerges in the form of Tagged Sets and Ensembles [47,48], see also the Definition 1 and Definition 8 of the Appendix A. 

Calculation of the molecular electrostatic potential distribution reveals that the steroid skeleton is surrounded by a positive field Figure 4.7), the charge of which stems from the CH bonds [134]. The facing amino acid side-chains of the binding subsite may then be supposed to carry negative... 

FI G U RE 28.10 The electrostatic potential distribution for the model I of hydrated state of silica surface. The p distribution within the plane perpendicular to the water molecule plane is given in upper left part of the picture. Isopotential lines correspond to p values in kJ/mol. 

The calculation on electrostatic potential distribution was carried out in accordance with the procedure described in [132] in two-centred approximation without a preliminary orthogonalization of atomic basis. 

Anisotropic Molecular Electrostatic Potential Distribution Around Atoms I 525... 

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