movies

Movies

Videos from some our research simulations

Adsorption and diffusion in carbon nanotubes

This movie shows NVE simulations of ethane inside carbon nanotubes at three different loadings. Some of the molecules are tinted red for visualization purposes. If you look closely, you can spot, in the top two cases, a helical diffusion path, unique to elongated rigid molecules within one dimensional carbons. This trajectory has to do with the chirality of the nanotubes, (in this case we use zig-zag single wall tubes).

Work done in collaboration with Dr. Fernando Cruz. More details in the full publication.

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Self assembly of polyphilic molecules

The picture below shows the first documented movie which describes the coarse grained self-assembly of a liquid crystal which has a lateral perfluorinated side chain from an isotropic fluid. We use Temperature Quench MD simulations for this. If you are patient enough to follow the simulation to the end, you will see how the system forms a columnar-like phase. Bear in mind that this is a pure fluid, not a mixture; the different colors represent the different parts of the molecule; the green beads correspond to the rigid liquid crystal core of the molecule, the orange beads correspond to the associating ends of the liquid crystal core, the blue spheres correspond to a flexible lateral chain.

Work done in collaboration with Francisco Martinez, Fernando Escobedo and Andrew J. Crane. More of this in a recent Soft Matter paper.

Music by Huey Lewis used without permission only for amusement purposes and under the "fair use" principle of copyright law.

Interfacial properties of fluids

We use both MD and the test-area method to investigate and quantify the interfacial properties of complex fluids and mixtures. The movie below shows the interfase of an n-decane - ethanol mixture.

The test-area method is well documented in these references

Adsorption of water + methane + CO2 in carbon nanopores

This is non-equilibrium MD simulation, where an equimolar mixture of methane (blue) and CO2 (green) with a 10% water (red/white) content is placed in contact with a carbon slit pore of 1.5 nm width (measured between the centers of the carbon atoms in the walls). Initially the mixture is placed in a the left hand side of the pore, with a vacuum on the right. The diffusion in initially very fast, and the pore is rapidly filled with the fluid. From then on, a slower process is observed as the system attempts to reach its equilibrium state, both mechanically (pressure-wise) and diffusive (concentration-wise). A very noticeable feature of this process is how water clusters and later resides within the pore, in spite of its macroscopically hydrophobic nature. A minute quantity of water will enter the pore and hinder the diffusion of the other two gases. However, larger quantities of water will not enter the pore and thus will not interfere with the gas diffusion.

We first pointed out the appearance of these clustering mechanisms water clusters in this paper

Music by Ole's used without permission only for amusement purposes and under the "fair use" principle of copyright law.

A version of this video competed in the 2009 RidgeDance Nanoscience Film Festival. Gold palm, no less.. Watch it here

Flow of CO2 through different porous media

This is non-equilibrium MD simulation as above, where pure CO2 is placed in contact with three different porous media with similar porosities (in terms of free volumes) but very different topologies.

This work is part of Alaaeldin Salih's Ph.D. thesis @ Imperial College

Properties of athermal systems

Athermal (non-attracting) spheres present a phase change when the packing fraction exceeds a value of 0.494. Fluid-fluid phase separations in "hard" systems are much more difficult to encounter. This MD simulation shows the onset of phase separation between a large colloids (black) and a collection of polymer molecules.

For papers on the shape factor and equations of state for non-spherical systems please see

N. F. Carnahan and E. A. Müller , Phys. Chem. Chem. Phys. 8, 2619-2623 (2006)

N. F. Carnahan, E. A. Müller, J. Pikunic , Phys. Chem. Chem. Phys. 1, 4259-4266 (1999)

For papers on binary and polydisperse hard sphere packing

E. Santiso and and E. A. Müller , Mol. Phys. 100, 2461-2469 (2002)

Notes: This are our first attempts to "publish" our movies. The quality is rather crude, however the original files would be too large to be placed here. If you wish to discuss any aspect, please e-mail me here (e 'dot' muller "at" imperial "dot" ac "dot" uk)

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Go to my Imperial College webpage

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If a picture is worth one thousand words, what is a video worth?