• Modeling and Simulation of Complex Molecular Systems

Research


Models

"Models are ways for our minds to make sense of observed phenomena in terms of concepts that are familiar to us, concepts that we can get our heads around."
Melanie Mitchell


Ion transport through ion channels and nanopores

This project aims modeling natural (ion channels) and synthetic nanopores that cross a natural (biological bilayer) or synthetic (plastic or solid state) membranes. Nanopores facilitate the transport of ions between two bulk electrolytes in a regulated manner that makes nanopores essential building blocks of nanodevices. [more]

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Modeling the eletrical double layer

This project aims modeling the electrical double layer formed by dissolved ions near charged surfaces such as electrodes, membranes, macromolecules. [more]

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II+IW model for the activity of electrolytes

We proposed a simple, but successful model for the non-monotonic concentration dependence of the activity coefficient of aqueous electrolytes. [more]

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Orientational and positional ordering of nonspherical particles in bulk

The effects of varying shape and anisotropic attraction are examined in the stabilisation of different mesophases such as the nematic, smectic and columnar phases. We are interested both in  convex (ellipsoidal, cylindrical) and nonconvex shapes (fused hard spheres, top-shaped particles). The differences in the shape and in the size are also considered in binary mixtures (rod-plate mixture, mixture of short and long rods, mixture of thin and thick cylinders). We use the classical density functional theory (DFT) to obtain the equilibrium density profile and the phase boundary.

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Effect of confinement on ordering properties of hard body fluids

The competition between wall-particle and particle-particle interactions is examined in narrow slit-like pores, where the shape of the particle is anisotropic. We find planar and homeotropic anchoring, biaxial surface ordering, layering transition and capillary nematisation. We use simplified models to solve the Euler-Lagrange equation for the density distribution function.

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Thermodynamics of quasi-one-dimensional fluids

Exact solutions are obtained with the help of the transfer-operator method for hard object moving on a line or confined into narrow pores, where only fist- and second-neighbor interactions are allowed. The shape of the object can be spherical and nonspherical both in two and three dimensions. Examples are the hard disks and hard rectangles in two dimensions, while the hard spheres and the hard boards in three dimensions.

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Molecular simulation of sheet silicates

Intercalation of layered clay minerals and separation of their layers are the principal methods for producing clay-polymer nanocomposites and inorganic nanostructures with advanced sorption and catalytic properties. Delamination of the platy 1:1 type clay mineral, kaolinite has been found to be one of the most promising ways to obtain curled aluminosilicate layers and aluminosilicate nanoscrolls. We model and evaluate the incorporation characteristics of primary, intermediate and final intercalation reagents in the interlayer space of kaolinite by classical molecular simulations.

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For the delamination of the kaolinite layers, a series of interdependent intercalation/deintercalation steps are applied, where, in the first (spontaneous) intercalation step, only a few selected small molecules can be used. The simulations were used to assist the explanation of how heat and other treatments impact on some intercalation/deintercalation routes and why certain molecules show advantageous properties in these procedures. By now the investigations with the primary and intermediate intercalation reagents have revealed two general features: (1) at least two different stable intercalation complexes can be found with the guest molecules, and (2) the guest molecules have significantly stronger interactions with the octahedral surface of kaolinite.  


Separation efficiency of zeolites

Zeolites are different from other porous materials due to the high regularity of their structure that makes their high selectivity in catalytic and separation processes possible. We study the sorption and permeation properties of zeolites with various Si-Al ratios at atomic level to identify their equilibrium- and transport-selectivity properties. These investigations mainly use realistic classical force fields and standard molecular simulation techniques. However, to cope with the wide range of length and time scales of membrane processes, specific new techniques are also developed and/or implemented.

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Complex adaptive systems

What is common in complex systems in Physics, Biology and Society?

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