Non-monotonic phase behaviour of a mixture containing non-adsorbing particles and polymerising rod-like molecules.

Hypothesis: Previous works have shown that many-body interactions induced by dispersants with increasing correlation length will generate a diminishing two-phase region [Soft Matter 14, 6921 (2018)]. We conjecture that the attenuation of the depletion attraction due to many-body interactions is a ubiquitous phenomenon in medium-induced interactions. We propose mixtures of colloidal particles and rod-like polymers as a feasible experimental system for verifying these predictions, since the intra-molecular correlations are not screened in a good solvent for rod-like polymers as they are in flexible polymers.

Impact of effective polarisability models on the near-field interaction of dissolved greenhouse gases at ice and air interfaces.

We present a theory for Casimir-Polder forces acting on greenhouse gas molecules dissolved in a thin water film. Such a nano-sized film has been predicted to arise on the surface of melting ice as stabilized by repulsive Lifshitz forces. We show that different models for the effective polarisability of greenhouse gas molecules in water lead to different predictions for how Casimir-Polder forces influence their extractions from the melting ice surface.

Distance-Dependent Sign Reversal in the Casimir-Lifshitz Torque.

The Casimir-Lifshitz torque between two biaxially polarizable anisotropic planar slabs is shown to exhibit a nontrivial sign reversal in its rotational sense. The critical distance a_{c} between the slabs that marks this reversal is characterized by the frequency ω_{c}∼c/2a_{c} at which the in-planar polarizabilities along the two principal axes are equal. The two materials seek to align their principal axes of polarizabilities in one direction below a_{c}, while above a_{c} their axes try to align rotated perpendicular relative to their previous minimum energy orientation.

Effective Polarizability Models.

Theories for the effective polarizability of a small particle in a medium are presented using different levels of approximation: we consider the virtual cavity, real cavity, and the hard-sphere models as well as a continuous interpolation of the latter two. We present the respective hard-sphere and cavity radii as obtained from density-functional simulations as well as the resulting effective polarizabilities at discrete Matsubara frequencies. This enables us to account for macroscopic media in van der Waals interactions between molecules in water and their Casimir-Polder interaction with an interface.

Volume dependence of the dielectric properties of amorphous SiO2.

Using first principles calculations, the analysis of the dielectric properties of amorphous SiO2 (am-SiO2) was performed. We found that the am-SiO2 properties are volume dependent, and the dependence is mainly induced by the variation of nanoporosity at the atomic scale. In particular, both ionic and electronic contributions to the static dielectric constants are functions of volume with clear trends.

A first principles study of CO2 adsorption on α-SiO2(001) surfaces.

In this work, using first principles calculations, an analysis of CO2 interaction with cleaved and reconstructed α-SiO2(001) surfaces was performed. We showed that CO2 could strongly interact with a cleaved surface forming CO3-like configurations. Here, the binding energy per CO2 molecule depends strongly on CO2 surface coverage and can reach -2.

Intermolecular Casimir-Polder forces in water and near surfaces.

The Casimir-Polder force is an important long-range interaction involved in adsorption and desorption of molecules in fluids. We explore Casimir-Polder interactions between methane molecules in water, and between a molecule in water near SiO(2) and hexane surfaces. Inclusion of the finite molecular size in the expression for the Casimir-Polder energy leads to estimates of the dispersion contribution to the binding energies between molecules and between one molecule and a planar surface.