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Theory and simulation of colloids near interfaces: quantitative mapping of interaction potentialsLu, Mingqing 15 May 2009 (has links)
The behavior of dense colloidal fluids near surfaces can now be probed in great
detail with experimental techniques like video and confocal microscopy. In fact we are
approaching a point where quantitative comparisons of experiments with particle-level
theory, such as classical density functional theory (DFT), are appropriate. In a forward
sense, we may use a known surface potential to predict a particle density distribution
function from DFT; in an inverse sense, we may use an experimentally measured
particle density distribution function to predict the underlying surface potential from
DFT. In this dissertation, we tested the ability of the closure-based DFT to perform
forward and inverse calculations on potential models commonly employed for colloidal
particles and surface under different surface topographies. To reduce sources of
uncertainty in this initial study, Monte Carlo simulation results played the role of
experimental data. The accuracy of the predictions depended on the bulk particle density,
potential well depth and the choice of DFT closure relationships. For a reasonable range
of choices of the density, temperature, potential parameters, and surface features, the
inversion procedure yielded particle-surface potentials to an accuracy on the order of 0.1
kBT. Our results demonstrated that DFT is a valuable numerical tool for microcopy
experiments to image three-dimensional surface energetic landscape accurately and
rapidly.
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