Dong J. Lee

A simplified model for the Briggs–Rauscher reaction mechanism

A model for the Briggs–Rauscher reaction mechanism with four intermediates and seven steps is proposed by simplifying the model of De Kepper and Epstein [J. Am. Chem. Soc. 104, 49 (1982)]. Assigning suitable rate constants for the steps of the simplified model, we obtain numerical results for the nonlinear dynamic behaviors such as oscillations, limit cycle, multistability, and inverse regulation of the iodine concentration. The results are compared with experiments and other previous models. The comparison shows that the present simplified model expresses the nonlinear dynamic behaviors better than the previous models.

Complex oscillations in a simple model for the Briggs-Rauscher reaction

Complex oscillations in a simple model of the Briggs-Rauscher reaction mechanism in a continuously stirred tank reactor proposed by Kim et al. [J. Chem. Phys. 117, 2710 (2002)] are investigated numerically. The k(0)-[CH(2)(COOH)(2)](0) phase diagram is constructed first where k(0) is the flow rate and [...](0) is the input concentration. Within the region surrounded by the Hopf bifurcation curve, we find complex oscillation regions which are again separated from the regular oscillation region by the secondary Hopf bifurcation curves. Mixed mode oscillations with an incomplete Farey sequence, periodic-chaotic (or nonperiodic) sequence, and various types of burst oscillations are observed in complex oscillation regions. Also, chaotic burst oscillations, which are due to the transition from one kind of burst to another kind, are reported.

THE SO(2,1) DYNAMIC-GROUP APPROACH TO THE ROTATION-VIBRATION SPECTRA OF DIATOMIC MOLECULES

Abstract The rotation—vibration spectra of diatomic molecules are discussed with the aid of the SO(2,1) dynamic group. The eigenvector of the compact generator is explicitly obtained by realizing the generators in the four-dimensoinal polar coordinates. A special representation of the radial part of the generators allows us to describe the discrete and continuous states of the Morse oscillator.

Monte Carlo Simulation of the Molecular Properties of Poly(vinyl chloride) and Poly(vinyl alcohol) Melts

NPT Monte Carlo simulations were performed to calculate the molecular properties of syndiotactic poly(vinyl chloride) (PVC) and syndiotactic poly(vinyl alcohol) (PVA) melts using the configurational bias Monte Carlo move, concerted rotation, reptation, and volume fluctuation. The density, mean square backbone end-to-end distance, mean square radius of gyration, fractional free-volume distribution, distribution of torsional angles, small molecule solubility constant, and radial distribution function of PVC at 0.1 MPa and above the glass transition temperature were calculated/measured, and those of PVA were calculated. The calculated results were compared with the corresponding experimental data and discussed. The calculated densities of PVC and PVA were smaller than the experimental values, probably due to the very low molecular weight of the model polymer used in the simulation. The fractional free-volume distribution and radial distribution function for PVC and PVA were nearly independent of temperature.

On the scattering phenomena for various kinds of polarized light in a nonpolar fluid composed of chiral molecules

The explicit result of the coefficients of the Mueller matrices, which express the Stokes parameters of single and double scattered lights in term of the parameters of the corresponding incident light, are obtained for a nonpolar fluid composed of chiral molecules with the aid of the Ornstein–Zernike form for the correlation function of density fluctuations. The explicit results show that any higher order multiple scattering satisfies the principle of symmetry and law of reciprocity. From the matrices some scattering phenomena for six kinds of completely polarized light in a nonpolar achiral fluid are discussed in the cases of far from and near the critical point. While the degrees of circularity (DCs) give identical information with the circular intensity differences (CIDs) in the region far from the critical point, the critical DCs for circularly polarized lights is quite different from the critical CIDs. The theoretical result of DCs for the circularly polarized lights indicates that the DCs can be oth...

On the critical behavior of phase changes of a forward-scattered light in an isotropic chiral fluid

Abstract The effect of density fluctuations on the changes of azimuth and ellipticity are analytically obtained in an isotropic chiral fluid, when the incident light is completely linearly polarized above (or below) the horizontal at 45°. The results are discussed in two extreme cases of the critical region.

The critical phase changes of a forward-scattered light in an isotropic chiral fluid

The phase changes of the forward-scattered light is explicitly obtained in an isotropic critical chiral fluid by using the Fisher correlation function of density fluctuations, when the incident light is completely linearly polarized above (or below) the horizontal at 45°. A new experiment method is suggested to measure the critical exponent for correlation function by using the result of azimuth changes of the scattered light.

The geometric effect of scattering space on the critical degree of circularity for Xe fluid

Abstract The geometric effect of scattering space are numerically discussed on the degree of circularity (DC) for Xe fluid in the critical region. The results show that the effect becomes very important, as the system approaches to the critical point and the DC can be another tool to study the critical scattering of a fluid.

On the scattering phenomena for various kinds of polarized light in a nonpolar binary liquid mixture

The explicit result for the Mueller matrix for the sum of single and double scatterings is obtained in a nonpolar binary liquid mixture composed of a chiral solute and an achiral solvent are obtained with the aid of the Ornstein–Zernike form for the correlation function of concentration fluctuations. The explicit result of the matrix shows that the law of reciprocity does not hold in the mixture. The scattering phenomena for six kinds of completely polarized light in a nonpolar binary liquid mixture are different from those in a pure chiral fluid because of the failure of the law and the large effect of concentration fluctuations. The scattering phenomena are in detail discussed in the region far from and near the critical point.

On the degress of circularity for various kinds of polarized light in a nonpolar liquid mixture

Abstract The explicit results of the degrees of circularity for various kinds of completely polarized light in a nonpolar binary liquid mixture composed of an optically active solute and an optically nonactive solvent are obtained with the aid of the Ornstein-Zernike form for the correlation function of density fluctuations. The results are discussed in detail far from and near the critical point and compared with circular intensity differences.