Dielectric relaxation computation

Single-step perturbation methods have also been applied to electrostatic processes. One study probed the dielectric properties of several proteins at a microscopic level [41,42], Test charges were inserted at many different positions within or around each protein, and a dielectric relaxation free energy was computed, which is related to a microscopic dielectric susceptibility (see Sect. 12.3). 

Hofinger S, Simonson T(2000) Dielectric Relaxation in Proteins A Continuum Electtostatic Model Incorporating Dielectric Heterogeneity of the Protein and Time-Dependent Charges, J Comput Chem, 22 290... 

In the second place, we shall study rotational dynamics. Rotational processes are of fundamental importance for dielectric relaxation. To shed light on some controversial issues in dielectric relaxation, Brot and co-workers did a computer simulation of a system of disks interacting via both Lennard-Jones potentials and electric dipole-dipole couplings. This is pre-... 

M. Neumann, Dielectric relaxation in water. Computer simulations with the TIP4P potential, J. Chem. Phys., 85 (1986) 1567-1580. 

Ionic Conductivity. The electrical conductivity measurements were performed using a Hewlett Packard model 4192 impedance analyzer under computer control, using a conductance cell similar to that described by Pauly and Schwan (5). The conductivity measurements were essentially constant between 1-100 kHz, ruling out electrode polarization or other artifacts. In 0/W microemulsions, no appreciable dielectric relaxation effects are expected or observed below 1 GHz (U. 

The molecular mechanisms for a number of these subglass transition relaxations have now been established, often by relating the temperature dependence of the frequency of the observed mechanical or dielectric relaxations to specific molecular motions, identified using either experiments (e.g., NMR and neutron scattering) or, more recently, computer simulations. By way of illustration, some examples of group motions that have been found to be active in a series of poly(alkyl methacrylate)s will be described in the following text. 

FIGURE 13.2 Arrhenius diagram of dielectric relaxation times of neatPA-1 IT 10 determined using TSC and DDS measurements. The dashed lines were computed from Eq. (13.2). 

The dielectric relaxation (DR) spectrum of pure water has been investigated in considerable detail by different experimental techniques, such as dielectric loss and, more recently, terahertz spectroscopy. The DR of water has also been investigated by computer simulations. However, the computational efforts have been relatively less successful because of the difficulty of simulating polarizable water molecules. 

E. Dachwitz, F. Parak, and M. Stockhausen, On the dielectric relaxation of aqueous myoglobin solutions. Ber. Bunsenges. Phys. Chem., 93 (1989), 1454 S. Boresch, P. Hochtl, and O. Steinhauser, Studying the dielectric properties of a protein solution by computer simulation. J. Phys. Chem. B, 104 (2000), 8743-8752. 

Computer Simulation of Dielectric Relaxation at Metal-Insulator Interfaces... 

The volume is divided into three parts Part I. Metallization Techniques and Properties of Metal Deposits, Part II, Investigation of Interfacial Interactions," and Part III, "Plastic Surface Modification and Adhesion Aspects of Metallized Plastics. The topics covered include various metallization techniques for a variety of plastic substrates various properties of metal deposits metal diffusion during metallization of high-temperature polymers investigation of metal/polymer inlerfacial interactions using a variety of techniques, viz., ESCA, SIMS, HREELS, UV photoemission theoretical studies of metal/polymer interfaces computer simulation of dielectric relaxation at metal/insulalor interfaces surface modification of plastics by a host of techniques including wet chemical, plasma, ion bombardment and its influence on adhesion adhesion aspects of metallized plastics including the use of blister test to study dynamic fracture mechanism of thin metallized plastics. 

A number of studies have been carried out of the glass transition process using dielectric relaxation spectroscopy. With the advent of computer-assisted measurements the DRS technique has increased in popularity and is now routinely used for the study of molecular mobility in polymeric materials. Chemical bonds may possess dipole moments as a consequence of the dilferences in... 

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