DSpace Collection:
https://dspace.lboro.ac.uk/2134/90
2017-03-28T08:05:10ZSolvent fluctuations around solvophobic, solvophilic and patchy nanostructures and the accompanying solvent mediated interactions
https://dspace.lboro.ac.uk/2134/24487
Title: Solvent fluctuations around solvophobic, solvophilic and patchy nanostructures and the accompanying solvent mediated interactions
Authors: Chacko, Blesson; Evans, Robert; Archer, Andrew J.
Abstract: Using classical density functional theory (DFT) we calculate the density profile ρ(r) and local compressibility χ(r) of a simple liquid solvent in which a pair of blocks with (microscopic) rectangular cross-section are immersed. We consider blocks that are solvophobic, solvophilic and also ones that have both solvophobic and solvophilic patches. Large values of χ(r) correspond to regions in space where the liquid density is fluctuating most strongly. We seek to elucidate how enhanced density fluctuations correlate with the solvent mediated force between the blocks, as the distance between the blocks and the chemical potential of the liquid reservoir vary. For sufficiently solvophobic blocks, at small block separations and small deviations from bulk gas-liquid coexistence, we observe a strongly attractive (near constant) force, stemming from capillary evaporation to form a low density gas-like intrusion between the blocks. The accompanying χ(r) exhibits structure which reflects the incipient gas-liquid interfaces that develop. We argue that our model system provides a means to understanding the basic physics of solvent mediated interactions between nanostructures, and between objects such as proteins in water, that possess hydrophobic and hydrophilic patches.
Description: This is the peer reviewed version of the following article: CHACKO, B., EVANS, R. and ARCHER, A.J., 2017. Solvent fluctuations around solvophobic, solvophilic and patchy nanostructures and the accompanying solvent mediated interactions. The Journal of Chemical Physics, 146 (12), 124703, which has been published in final form at http://dx.doi.org/10.1063/1.4978352.2017-01-01T00:00:00ZProbabilistic approach to nonlinear wave-particle resonant interaction
https://dspace.lboro.ac.uk/2134/24397
Title: Probabilistic approach to nonlinear wave-particle resonant interaction
Authors: Artemyev, A.V.; Neishtadt, Anatoly; Vasiliev, Alexei; Mourenas, D.
Abstract: In this paper we provide a theoretical model describing the evolution of the charged particle distribution function in a system with nonlinear wave particle interactions. Considering a system with strong electrostatic waves propagating in an inhomogeneous magnetic field, we demonstrate
that individual particle motion can be characterized by the probability of trapping into the resonance with the wave and by the efficiency of scattering at resonance. These characteristics, being derived for a particular plasma system, can be used to construct a kinetic equation (or generalized Fokker-Planck equation) modelling the long-term evolution of the particle distribution. In this equation, effects of charged particle trapping and transport in phase space are simulated with a nonlocal
operator. We demonstrate that solutions of the derived kinetic equations agree with results of test particle tracing. The applicability of the proposed approach for the description of space and laboratory plasma systems is also discussed.
Description: This paper was accepted for publication in the journal Physical Review E and the definitive published version is available at https://doi.org/10.1103/PhysRevE.95.0232042017-01-01T00:00:00ZFunctional integral representations of the Pauli-Fierz model with spin 1/2
https://dspace.lboro.ac.uk/2134/24097
Title: Functional integral representations of the Pauli-Fierz model with spin 1/2
Authors: Hiroshima, Fumio; Lorinczi, Jozsef
Abstract: A Feynman–Kac-type formula for a Lévy and an infinite-dimensional Gaussian random process associated with a quantized radiation field is derived. In particular, a functional integral representation of e−tHPF generated by the Pauli–Fierz Hamiltonian with spin 1/2 in non-relativistic quantum electrodynamics is constructed. When no external potential is applied HPF turns translation-invariant and it is decomposed as a direct integral HPF=∫R3⊕HPF(P)dP. The functional integral representation of e−tHPF(P) is also given. Although all these Hamiltonians include spin, nevertheless the kernels obtained for the path measures are scalar rather than matrix expressions. As an application of the functional integral representations energy comparison inequalities are derived.2008-01-01T00:00:00ZInfluence of the fluid structure on the binding potential: comparing liquid drop profiles from density functional theory with results from mesoscopic theory
https://dspace.lboro.ac.uk/2134/24063
Title: Influence of the fluid structure on the binding potential: comparing liquid drop profiles from density functional theory with results from mesoscopic theory
Authors: Hughes, Adam P.; Thiele, Uwe; Archer, Andrew J.
Abstract: For a film of liquid on a solid surface, the binding potential $g(h)$ gives the free energy as a function of the film thickness $h$ and also the closely related structural disjoining pressure $\Pi = - \partial g / \partial h$. The wetting behaviour of the liquid is encoded in the binding potential and the equilibrium film thickness corresponds to the value at the minimum of $g(h)$. Here, the method we developed in [J. Chem. Phys. 142, 074702 (2015)], and applied with a simple discrete lattice-gas model, is used with continuum density functional theory (DFT) to calculate the binding potential for a Lennard-Jones fluid and other simple liquids. The DFT used is based on fundamental measure theory and so incorporates the influence of the layered packing of molecules at the surface and the corresponding oscillatory density profile. The binding potential is frequently input in mesoscale models from which liquid drop shapes and even dynamics can be calculated. Here we show that the equilibrium droplet profiles calculated using the mesoscale theory are in good agreement with the profiles calculated directly from the microscopic DFT. For liquids composed of particles where the range of the attraction is much less than the diameter of the particles, we find that at low temperatures $g(h)$ decays in an oscillatory fashion with increasing $h$, leading to highly structured terraced liquid droplets.
Description: This paper was accepted for publication in the journal Journal of Chemical Physics.2017-01-01T00:00:00Z