Molecular dynamics conductors

Berendsen, H.J.C. Van Gunsteren, W.F. Molecular dynamics with constraints, in The Physics of Superionic Conductors and Electrode Materials ed. J.W. Perram, NATO ASI Series B 92 (1983) 221-240 (Plenum, New York). 

Vl L, J R Walker and C R A Catlow 1984. A Molecular Dynamics Simulation Study of the iperionic Conductor Lithium Nitride I. Journal of Physical Chemistry 17 6623-34. 

Solvatochromic shifts for cytosine have also been calculated with a variety of methods (see Table 11-7). Shukla and Lesczynski [215] studied clusters of cytosine and three water molecules with CIS and TDDFT methods to obtain solvatochromic shifts. More sophisticated calculations have appeared recently. Valiev and Kowalski used a coupled cluster and classical molecular dynamics approach to calculate the solvatochromic shifts of the excited states of cytosine in the native DNA environment. Blancafort and coworkers [216] used a CASPT2 approach combined with the conductor version of the polarizable continuous (CPCM) model. All of these methods predict that the first three excited states are blue-shifted. S i, which is a nn state, is blue-shifted by 0.1-0.2 eV in water and 0.25 eV in native DNA. S2 and S3 are both rnt states and, as expected, the shift is bigger, 0.4-0.6eV for S2 and 0.3-0.8 eV for S3. S2 is predicted to be blue-shifted by 0.54 eV in native DNA. 

Sprik et al, 1993 Signorini et al, 1990), a typical example being the orientational disorder associated with NH in NH Br. Detailed simulations have been reported on (NaCN),, t(KCN),t and other mixed alkali halides and alkali cyanides. Other systems studied include potassium and calcium nitrate crystals and their mixtures. The transition from the crystalline to the superionic conductor phase in solid electrolytes has also been successfully investigated. Molecular dynamics studies of Agl were carried out by Parrinello, Rahman Vashishta (1983). LijSO has been investigated by molecular dynamics by Impey et al. (1985). Here, the Li ions become mobile at high temperatures. The ions exhibit orientational disorder and the orientational... 

After 14 years on the faculty of Imperial College, Jacobs moved from London, England, to London, Ontario, where his research program focused on the optical and electrical properties of ionic crystals, as well as on the experimental and theoretical determination of thermodynamic and kinetic properties of crystal defects.213 Over the years his research interests have expanded to include several aspects of computer simulations of condensed matter.214 He has developed algorithms215 for molecular dynamics studies of non-ionic and ionic systems, and he has carried out simulations on systems as diverse as metals, solid ionic conductors, and ceramics. The simulation of the effects of radiation damage is a special interest. His recent interests include the study of perfect and imperfect crystals by means of quantum chemical methods. The corrosion of metals is being studied by both quantum chemical and molecular dynamics techniques. 

We have previously presented results of calculations showing that polymer nanoparticles with excess electrons exhibit discrete electronic structure and chemical potential in close analog with semi-conductor quantum dots. The dynamics of the formation of polymer nanoparticles can be simulated by the use of molecular dynamics and the morphology of these particles may be predicted. The production method that is used for the creation of these polymer particles can also be used to mix polymer components into a nanoparticle when otherwise they are immiscible in the bulk Quantum drops, unlike the semiconductor quantum dots, can be generated on demand and obtained in the gas phase. In the gas phase, these new polymer nanoparticles have the capacity to be used for catalytic purposes which may involve the deUveiy of electrons with chosen chemical potential. Finally, quantum drops have unusual properties in magnetic and electric fields, which make them suitable for use in applications ranging from catalysis to quantum computation. 

At high temperatures, terraces appear to produce most adatoms. Activation energies for mass transfer diffusion are therefore higher than at low temperatures. Evidence for this effect comes from molecular dynamics simnlations for self-diffusion on Lennard-Jones solids [94Sunl] and semi-conductors [96Sunl, 96A111]. The simulations show that the number of adatom-vacancy pairs produced from terraces increases... 

Kinetic theory, non-equilibrium statistical mechanics and non-equilibrium molecular dynamics (NEMD) have proved to be useful in estimating both straight and cross-coefficients such as thermal conductivity, viscosity and electrical conductivity. In a typical case, cross-coefficient in case of electro-osmosis has also been estimated by NEMD. Experimental data on thermo-electric power has been analysed in terms of free electron gas theory and non-equilibrium thermodynamic theory [9]. It is found that phenomenological coefficients are temperature dependent. Free electron gas theory has been used for estimating the coefficients in homogeneous conductors and thermo-couples. 

Several groups have also made relevant contribution to the evolution of the original PCM. A related model based on conductor-like screening (COSMO) has been developed recently by Klamt and Schuiirmann [13]. Likewise, another approach to the PCM has been proposed in which the cavity surface is determined in terms of an electronic isodensity surface [14]. Olivares del Valle and coworkers [15] have focused their attention on aspects such as the inclusion of correlation effects in the PCM, or on the role of nonadditive effects in solute-solvent interactions. Pascual-Ahuir et al. [16] have paid most attention to the problem of the definition of the cavity surface. The work done in Barcelona has focussed mainly on the parametrization of the PCM to treating aqueous and nonaqueous solvents, as well as the application of the PCM to the study of biochemical systems [17, 18]. Finally, we and others have made new methodological developments to allow the implementation of the PCM in molecular dynamics or in Monte Carlo calculations [19]. 

Apart from crystalline phases, various glassy solid F conductors have also been developed. A glass in the ZrF4-BaF2 system, the first example of such conductors, exhibits a conductivity of 10" S cm" at 200°C.2 Extensive studies have been performed with this system, including short-range stractural analyses, T NMR, simulation based on molecular dynamics, etc. According to the results, there are basically two kinds of fluorine ions, i.e., a... 

Single-ion conductors can be obtained by the intercalation of PEO on clay due to the presence of cation charge at the silicate surface. The conductivity values of electrolytes based on POEM with the addition of 2 and 5 wt% clay were found to be around 4 x 10 S/cm at 70 °CF The conductivity obtained can be anisotropic. Molecular dynamic simulation has shown that the Li" ions are solvated preferentially by the silicate oxygen atom rather than PEO. The conductivity is too low for practical applications, even with a cationic transference number equal to one. In order to increase conductivity, but with a cationic transference number different from one, lithium salts were added to PEO/clay nanocomposites. At room temperature, the nanocomposite electrolyte exhibited higher ionic conductivity than unfilled polymer due to the larger content of the PEO amorphous phase. The improvement in conductivity depends on the nature of the clay. Fan et al. have shown that 250-Li-MMT, i.e. Li-MMT heated to 250°C, was more effective in enhancing the conductivity of (PE0)i6LiC104 than Org-MMT, dodecylamine modified Li-MMT, and Li-MMT, since 250-Li-MMT forms an exfoliated structure in the PEO matrix. 

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