Electrostatic potential and

Ferenczy G G, C A Reynolds and W G Richards 1990. Semi-Empirical AMI Electrostatic Potentials and AMI Electrostatic Potential Derived Charges - A Comparison with Ah Initio Values. Journal of Computational Chemistry 11 159-169. 

Hodgkin E E and W G Richards 1987. Molecular Similarity Based on Electrostatic Potential and Electri Field. International Journal of Quantum Chemistry. Quantum Biology Symposia 14 105-110. 

Many molecular properties can be related directly to the wave function or total electron density. Some examples are dipole moments, polarizability, the electrostatic potential, and charges on atoms. 

Once the job is completed, the UniChem GUI can be used to visualize results. It can be used to visualize common three-dimensional properties, such as electron density, orbital densities, electrostatic potentials, and spin density. It supports both the visualization of three-dimensional surfaces and colorized or contoured two-dimensional planes. There is a lot of control over colors, rendering quality, and the like. The final image can be printed or saved in several file formats. 

The point r is the position of a positive probe charge. is the nuclear charge on atom Alocated at position R. The function p(r ) is the electronic density. In the above equation, the first term represents the contribution of the nuclei to the electrostatic potential and the second term is the electronic contribution. Substituting the electron density expression ... 

Compare electrostatic potential maps for propane, acetone and 2,4-pentanedione, and identify the most positively-charged acidic hydrogen(s) in each. Is there a correlation between electrostatic potential and pK (see table at right) ... 

The Polarizable Continuum Model (PCM) employs a van der Waals surface type cavity, a detailed description of the electrostatic potential, and parameterizes the cavity/ dispersion contributions based on the surface area. The COnductor-like Screening... 

Functionalized polyelectrolytes are promising candidates for photoinduced ET reaction systems. In recent years, much attention has been focused on modifying the photophysical and photochemical processes by use of polyelectrolyte systems, because dramatic effects are often brought about by the interfacial electrostatic potential and/or the existence of microphase structures in such systems [10, 11], A characteristic feature of polymers as reaction media, in general, lies in the potential that they make a wider variety of molecular designs possible than the conventional organized molecular assemblies such as surfactant micelles and vesicles. From a practical point of view, polymer systems have a potential advantage in that polymers per se can form film and may be assembled into a variety of devices and systems with ease. 

In the following chapters, we will concern ourselves with the nature of the interfacial microenvironments of some polyelectrolytes whose functionality controls photoinduced ET. Emphasis will be placed on the local electrostatic potential and also on the microphase structure of some amphiphilic polyelectrolytes in aqueous solution. 

A merocyanine dye, l-ethyl-4-(2-(4-hydroxyphenyl)ethenyl)pyridinium bromide (M-Mc, 2), exhibits a large spectral change according to the acid-base equilibrium [40, 41]. The equilibrium is affected by the local electrostatic potential and the polarity of the microenvironment around the dye. Hence, this dye is useful as a sensitive optical probe for the interfacial potential and polarity when it is covalently attached to the polyelectrolyte backbone. 

The actual state, and absolute amount, of intrinsic energy existing in a body, or system of bodies, are things which lie quite outside the range of pure thermodynamics. This indefiniteness has, however, not the slightest influence on the stringency of the definition, since we can proceed as in the definition of electrostatic potential, and choose any convenient standard state of the body, and use the term intrinsic energy with reference to this standard state. 

For the electrostatic potential and the surface form, similar to the asymmetrical fluctuations, the following symmetrical fluctuations can be defined ... 

The integral is taken along a trajectory I parallel to the optical axis, passing inside and outside the specimen, and which must include stray fields V(f, z) and Az(r, z) are the electrostatic potential and the z component of the magnetic vector potential A(f,z), respectively E a factor that becomes the accelerating voltage in the non-relativistic... 

Here G is the Gibbs free energy of the system without external electrostatic potential, and qis refers to the energy contribution coming from the interaction of an apphed constant electrostatic potential s (which will be specified later) with the charge qt of the species. The first term on the right-hand side of (5.1) is the usual chemical potential /r,(T, Ci), which, for an ideal solution, is given by... 

Fig. 3 Due to the anisotropic distribution of the electron density, halogen atoms show a negative electrostatic potential and a larger radius (rmax) in the equatorial region and a positive electrostatic potential and a smaller radius (rmjn) in the polar region. As a consequence of this, halogens behave as nucleophiles at the equator and as electrophiles at the pole...

Reynolds CA, Ferenczy GG, Richards WG (1992) Methods for determining the reliability of semiempirical electrostatic potentials and potential derived charges. Theochem J Mol Struct 88,... 

The DLVO theory, with the addition of hydration forces, may be used as a first approximation to explain the preceding experimental results. The potential energy of interaction between spherical particles and a plane surface may be plotted as a function of particle-surface separation distance. The total potential energy, Vt, includes contributions from Van der Waals energy of interaction, the Born repulsion, the electrostatic potential, and the hydration force potential. [Israelachvili (13)]. 

The scheme for obtaining the electron density is thus as follows, (i) Given an electron density n(r), one can construct the electrostatic potential and 8sxc/8n. (ii) This gives the potential V and the Hamiltonian h. (iii) The eigenfunctions of h are found and combined into a new electron density, (iv) One seeks self-consistency i.e., input and output electron densities should be identical. In principle, though not in practice, this involves iteration of steps (i)-(iii). With the self-consistent functions, G[n] is written as... 

In this chapter, we have sought to convey some appreciation of the sort of questions that can and have been addressed by means of the electrostatic potential, and further to indicate... 

Ferenczy, G. G., C. A. Reynolds, and W. G. Richards. 1990. Semiempirical AMI Electrostatic Potentials and AMI Electrostatic Potential Derived Charges A Comparison with ab initio Values. J. Comp. Chem. 11, 159. 

Lavery, R., S. Corbin, and B. Pullman. 1982. The Molecular Electrostatic Potential and Steric Accessibility of C-DNA. Theor. Chim. Acta 60, 513. 

Murray, J. S., S. G. Gagarin, and P. Politzer. 1995. Representation of Cg0 Solubilities in Terms of Computed Molecular Surface Electrostatic Potentials and Areas. J. Phys. Chem. 99,12081. 

Politzer, P., P. Lane, J. S. Murray, and T. Brinck. 1992a. Investigation of Relationships Between Solute Molecule Surface Electrostatic Potentials and Solubilities in Supercritical Fluids. J. Phys. Chem. 96, 7938. 

Politzer, P., and I. S. Murray. 1991. Molecular Electrostatic Potentials and Chemical Reactivity. In Reviews in Computational Chemistry. K. B. Lipkowitz and D. B. Boyd, eds. VCH Publishers, New York. 

To compute electrostatic potential and field distributions in very complex geometries, this equation, or one of its subsidiaries, can be solved numerically subject to a set of boundary conditions (McAllister et al.,... 

The model that utilized regression analysis was one that built upon previous work by the same authors [36,39]. In this case, the dataset was expanded to 125-129 drugs and the number of assessed descriptors increased to 210. Models for acidic and basic compounds were developed separately as well as a model using all compounds, and the advantages of analyzing acids and bases separately were minimal. Mean-fold errors were generally around 1.8. Descriptors that dominated the models included lipophilicity, fraction anionic or cationic, surface electrostatic potential, and parameters specific to aliphatic carbons and fluorine. 

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