Dynamic nanoscale volumes

Nanoscale molecules and molecular assemblies are being used more and more frequently as they reduce costs and use fewer resources. In order to be able to analyze and characterize these materials, new techniques have to be developed or refined. This two-volurne work brings together the knowledge from research and from industry of molecular nano dynamics. The topics are clearly divided into five parts over the 2 volumes, which focus on different topics. 

In addition to the described above methods, there are computational QM-MM (quantum mechanics-classic mechanics) methods in progress of development. They allow prediction and understanding of solvatochromism and fluorescence characteristics of dyes that are situated in various molecular structures changing electrical properties on nanoscale. Their electronic transitions and according microscopic structures are calculated using QM coupled to the point charges with Coulombic potentials. It is very important that in typical QM-MM simulations, no dielectric constant is involved Orientational dielectric effects come naturally from reorientation and translation of the elements of the system on the pathway of attaining the equilibrium. Dynamics of such complex systems as proteins embedded in natural environment may be revealed with femtosecond time resolution. In more detail, this topic is analyzed in this volume [76]. 

Work on supramolecular shirctures has opened access to useful nanocomposites by influencing phase-separating fluids. Simulations show tliat when low-volume fractions of nanoscale rods are immersed in a binary, phase-separating blend, the rods self-assemble into needle-like, percolating networks. The interconnected network arises tlir ough the dynamic interplay of phase-separation between the fluids, through preferential adsorption of... 

NANOSCALE OPTICAL PROBES OF POLYMER DYNAMICS IN ULTRASMALL VOLUMES... 

The contributions to this volume cover applied topics such as hierarchically structured materials, molecular reaction dynamics, chemical catalysis, thermodynamics of aggregated phases, molecular self-assembly, chromatography, nanoscale... 

Creep rate spectroscopy allowed us not only to estimate the dynamic heterogeneity but also to probe local (nanoscale) compositional inhomogeneity in the PU-BMA copolymer IPNs. For this purpose, the relative peak contributions to dynamics around Tg as a function of IPN composition were estimated. On this basis, the volume fractions of the nanodomains of neat constituent networks as well as their miscibility degree as a function of IPN composition could be determined, in a semi-quantitative way [133]. 

However, the length and time scales that molecular-based simulations can probe are still very limited (tens of nanosecond and a few nanometers), due to computer memory and CPU power limitations. On the other hand, nanoscale flows are often a part of larger scale devices that could contain both nanochannels and microfluidic domains. The dynamics of these systems depends on the intimate connection of different scales from nanoscale to microscale and beyond. MD simulation cannot simulate the whole systems due to its prohibitive computational cost, whereas continuum Navier-Stokes simulation cannot elucidate the details in the small scales. These limitations and the practical needs arising from the study of multiscale problems have motivated research on multiscale (or hybrid) simulation techniques that bridge a wider range of time and length scales with the minimum loss of information. A hybrid molecular-continuum scheme can make such multiscale computation feasible. A molecular-based method, such as MD for liquid or DSMC for gas, is used to describe the molecular details within the desired, localized subdomain of the large system. A continuum method, such as finite element or finite volume based Navier-Stokes/Stokes simulation, is used to describe the continuum flow in the remainder of the system Such hybrid method can be applied to solve the multiscale phenomena in gas, liquid, or solid. 

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