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The 2-norbornyl cation is an old topic in physical-organic chemistry. Whether in classical or non-classical form (partial bridged form) it has been one of the focus of discussion. Currently the experimental data and theoretical calculations favorably support the idea that 2-norbornyl cation is not in the classical form in the stable-ion condition. In this paper, first, we will show that a 3-center-2-electron π-complex is formed by the collapse of 2-norbornyl cation. Further, using different theoretical methods (B3LYP, MP2) with different basis sets (6-31+G, 6-31G(d,p), 6-311G(d,p), 6-311G(2d,p)), we find that there is a trend for the 3-center-2-electron π-complex to approach the Cs symmetry, and this π-complex oscillates within the numerical limits of the perfect Cs symmetrical configuration. The stabilization energies of the π-complex are 13.87 Kcal/mol and 19.47 Kcal/mol by B3LYP/6-31+G and MP2/6-31+G, respectively. Second, our calculations also show that the transition state between 2-norbornyl cation and 3-norbornyl cation is formed by a 3, 2-proton shift, not the generally accepted 3, 2-hydride shift. The activation energy of this 3, 2-proton shift is 10.9 Kcal/mol. Detailed structural changes in the optimization process and the formation of transition state (also a 3-center-2-electron π-complex) between 2-norbornyl cation and 3-norbornyl cation will also be included. [ABSTRACT FROM AUTHOR]

We have calculated the structures, the heats of hydrogenation and the resonance energies of benzene isomers. All structures and energies were calculated by using the MMX force fields. Using PC model, the calculated structure parameters of benzene's 8 isomers are generally in good agreements with the experimental data. The heats of hydrogenation and resonance energy of benzene isomers are parallel to those experimental data and need a systematic adjustment of 4.5 kJ/mol. [ABSTRACT FROM AUTHOR]

We present the iFACE system, a visual speech synthesizer that provides a form of virtual face-to-face communication. The system provides an interactive tool for the user to customize a graphic head model for the virtual agent of a person based on his/her range data. The texture is mapped onto the customized model to achieve a realistic appearance. Face animations are produced by using text stream or speech stream to drive the model. A set of basic facial shapes and head action is manually built and used to synthesize expressive visual speech based on rules. [ABSTRACT FROM AUTHOR]

This paper describes some issues in building a 3-D human face modeling system which mainly consists of three parts: • Modeling human faces; • Analyzing facial motions; • Synthesizing facial expressions. A variety of techniques developed for this system are described in detail in this paper. Some preliminary results of applying this system to computer animation, video sequence compression and human face recognition are also shown. [ABSTRACT FROM AUTHOR]