We describe three simple models for electronic structure in many-electron atoms and ions. Each model is parametrized by the spatial dimensionality D, which is ordinarily set to 3. All procedures are motivated by the solution for D -+ 00, a classical limit which can be solved exactly either with or without electron correlation. Each model modifies the D -+ 00 limit treatment to reflect important finite-D effects, but retains the classical character of the limit; the modifications, in order of increasing realism, are designated post-scaling, pre-scaling, and pre-structuring. The three models yield pointlike electronic structures somewhat reminiscent of pre-quantal atomic models. However, all electronic positions have components outside the D-dimensional physical subspace, a feature which significantly enhances the ability of a localized structure to represent the true solution and to model it quantitatively. Specific calculations reported are total and correlation energies for atoms with Z :s;; 92 (computed by post-scaling and pre-scaling), correlation corrections to ionization potentials and electron affinities for Z :s;; 54 (post-scaling), and the asymptotic behavior of correlation energies for Z -+ 00 (post-scaling).
Much of the traditional general chemistry class focuses on the nuts and bolts of chemical calculations. As a result it is often difficult to infuse the class with timely chemistry topics. This Journal has provided some excellent applications over the years (1-8).The current government interest in nicotine conversion by cigarette companies (9) provides an example of acid-base chemistry that can be explained to students in the second college semester of general chemistry. The discussion of acid-base chemistry tends to coincide with the students' preregistration for the next semester's organic chemistry class. Organic chemistry has a notorious reputation. Thus students tend to be anxious about this future class. One result of this anxiety is that although the explanation for nicotine conversion relies on organic acid-base chemistry, the students are particularly interested because organic chemistry is already on their minds. This example is also suitable for an AP high school chemistry class, but is probably too advanced for an introductory high school course.The weak base ammonia is often added to cigarette tobacco (10). The U.S. Food and Drug Administration (FDA) has argued that this added ammonia enhances the delivery of nicotine into the smoker's bloodstream. In contrast, tobacco companies argue that it is important to know as much as possible about nicotine chemistry in order to provide smoker satisfaction, and this knowledge is the underlying reason for their interest in ammonia as an additive (11).
Lithium ion (Li-ion) batteries have become a promising alternative power source in electric vehicles (EVs) due to their high nominal cell voltage, high energy density, long life and not having a memory effect. However temperature effect and dynamic characteristic of the li-ion batteries greatly affects their performance. In this study, a dynamic model of li-ion battery has been developed by MATLAB/Simulink and simulated at different temperatures. Simulink model contains dynamic circuit parameters as a function of state of charge and temperature effect. Simulation results show that proposed dynamic model is effective and operational under the different temperature rates for dynamic output characteristic of li-ion battery.
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