Effective charge model

Kikuchi, O., T. Natsui, and T. Kozaki. 1990a. MNDO Effective Charge Model Study of Conformations of Zwitterionic and Neutral Forms of Glycine, Alanine and Serine in the Gas Phase and in Solution. J. Mol. Struct. (Theochem) 207, 103-114. 

The effective CF models, intended to include covalence effects via effective charges and shielding parameters [46] (superposition model [47], effective charge model [48], simple overlap model [49, 50]), keep the radial (M-L distance) dependence of the CF parameters as in the simple (point charge) electrostatic model. Dedicated studies have shown, however, that the radial dependence of these parameters deviates strongly from the latter for the whole series of lanthanide ions [51, 52]. 

Perhaps the most informative studies (Anvia and Bowden, 1990) of leaving groups are of the alkaline hydrolysis of 3-substituted phenyl 2-acetyl- and 2-benzoyl-benzoates [20], The Hammett reaction constants p are ca. 0.50 and 1.48 for the 2-acetyl and 2-benzoyl esters respectively, as. shown in Table 2. These were compared with various limiting models in a similar manner to the effective charge model (Williams, 1984,1992). This comparison indicates that all simple phenyl esters of the latter types hydrolyse by a mechanism... 

T. Kozaki, M. Morihasi, and O. Kikuchi,/. Am. Chem. Soc., Ill, 1547 (1989). MNDO-Effective Charge Model Study of Solvent Effect on the Potential Energy Surface of the S, 2 Reaction. 

If one calculates the sensitivity coefficients of different properties of an aqueous system with respect to the atomic partial charges of the water models, the sensitivity coefficients obtained from an effective charge model can be different from those of a polarizable model. This difference was found in calculations of the charge sensitivities of different properties of liquid water with two effective charge models (the SPC and the TIP3P models ) and a polarizable water model > (Table 1), although the differences were more pronounced for sensitivity coefficients of some types than for others. Therefore, in using sensitivity coefficients to help identify the determinants of bio(molecular) proper-... 

Bars tar 4 bamase Electrostatic steering. Rates of association of wild-type and 11 mutant proteins computed in good agreement with experiment. Encounter complex shifted slightly from bound complex. Ionic-strength dependence well reproduced with effective charges model. 80... 

Since in the effective charge model the molecular dipole moment is defined by p = Z Ca fa [Eq- (3.54)], a Cartesian component of p may be represented as follows... 

Eckart, criteria, 264, 298 procedure, 267 Effective charge, 274, 276 Effective Hamiltonian, 226 Elastic model, excess entropy calculation from, 141 of a solid solution, 140 Electric correlation, 248 Electric field gradient, 188, 189 Electron (s), 200... 

Scientists at Bristol-Myers Squibb used the a-ketoamide functionality to extend binding to the prime side [147]. The glycine carboxylic acid (Compound (5), Table 2.5) was identified as the most effective extension. Modelling studies, coupled with SAR, suggested that there is either hydrogen bonding or a charge complex of the acid with Lys-136 and Arg-109. 

Sukumar, N., and G. A. Segal. 1986. Effect of Aqueous Solvation upon the Electronic Excitation Spectrum of the Glycine Zwitterion A Theoretical Cl Study Using a Fractional Charge Model. J. Am. Chem. Soc. 108, 6880-6884. 

Figure 3.68 Total reduction charge (+ ) for the outer film and water content ( ) of the outer film (as estimated from the effective medium model and the data at 633 nm (see text for details). Reprinted from Corrosion Science, 28, P. Southworth, A. Hamnett, A.M. Riley and J.M. Sykes, An Ellipsometric and RRDE Study of Iron Passivation and Depassivation in Carbonate BufTer, pp. 1139-1161 (1988), with kind permission from Pergamon Press Ltd., Headington Hill Hall,...

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