@article {2614,
	title = {Wall-colloid interaction in nematic solvents: external field effects},
	journal = {Journal of Physics-Condensed Matter},
	volume = {21},
	number = {24},
	year = {2009},
	note = {ISI Document Delivery No.: 453AETimes Cited: 1Cited Reference Count: 21Sokolovska, T. G. Patey, G. N.},
	month = {Jun},
	pages = {5},
	type = {Article},
	abstract = {We propose a molecular theory of colloid-wall interactions in nematic media that predicts a new effective force acting on colloidal particles in the presence of an external field. In contrast to the so-called {\textquoteright}image{\textquoteright} interaction that is always repulsive at long distances, the force identified here can be attractive or repulsive, depending on the type of anchoring at the wall and colloidal surfaces. The effective force on a colloidal particle decreases with distance s from the wall as exp(-s/xi), where xi is a magnetic (electric) coherence length. At weak fields the force is proportional to (Sigma/xi)(3) for {\textquoteright}quadrupolar{\textquoteright} colloids and to (Sigma/xi)(2) for {\textquoteright}dipoles{\textquoteright}, where Sigma is the colloidal diameter. A brief discussion of recent experiments in the light of our findings is presented.},
	keywords = {FORCES, LIQUID-CRYSTALS, PARTICLES, TOPOLOGICAL DEFECTS},
	isbn = {0953-8984},
	url = {<Go to ISI>://000266581500006},
	author = {Sokolovska, T. G. and Patey, G. N.}
}
@article {2256,
	title = {Bridging the gap between phenomenology and microscopic theory: Asymptotes in nematic colloids},
	journal = {Physical Review E},
	volume = {77},
	number = {4},
	year = {2008},
	note = {ISI Document Delivery No.: 295EDTimes Cited: 3Cited Reference Count: 28Sokolovska, T. G. Sokolovskii, R. O. Patey, G. N.Part 1},
	month = {Apr},
	pages = {10},
	type = {Article},
	abstract = {The Ornstein-Zernike equation is applied to nematic colloids with up-down symmetry to determine how the electrostatic analogy and other phenomenological results appear in molecular theory. In contrast to phenomenological approaches, the molecular theory does not assume particular boundary conditions (anchoring) at colloidal surfaces. For our molecular parameters the resulting anchoring appears to be realistic, neither rigid nor infinitely weak. For this case, the effective force between a colloidal pair at large separation remains essentially constant over the entire region of nematic stability. We show that a simple van der Waals approximation gives a potential of mean force that in some important aspects is similar to the phenomenological results obtained in the limit of weak anchoring; at large separations the potential varies as Sigma(8), where Sigma is the colloidal diameter. In contrast, the more sophisticated mean spherical approximation yields a Sigma(6) dependence consistent with phenomenological calculations employing rigid boundary conditions. We show that taking proper account of the correlation (or magnetic coherence) length xi inherent in the nematic sample is essential in an analysis of the Sigma dependence. At infinite xi the leading Sigma dependence is Sigma(6), but this shifts to Sigma(8) when xi is finite. The correlation length also influences the orientational behavior of the effective interaction. The so-called quadrupole interaction that determines the long-range behavior at infinite xi transforms into a superposition of screened "multipoles" when xi is finite. The basic approach employed in this paper can be readily applied to a broad range of physically interesting systems. These include patterned and nonspherical colloids, colloids trapped at interfaces, and nematic fluids in confined geometries such as droplets.},
	keywords = {ELASTIC-CONSTANTS, FIELD, FORCES, LIQUID-CRYSTALS, PARTICLES, PHASE, STATISTICAL-THEORY, TOPOLOGICAL DEFECTS},
	isbn = {1539-3755},
	url = {<Go to ISI>://000255456900069},
	author = {Sokolovska, T. G. and Sokolovskii, R. O. and Patey, G. N.}
}
@article {1260,
	title = {Nematic fluid structure in wall-field geometry},
	journal = {Journal of Chemical Physics},
	volume = {122},
	number = {3},
	year = {2005},
	note = {ISI Document Delivery No.: 893VPTimes Cited: 6Cited Reference Count: 31},
	month = {Jan},
	pages = {9},
	type = {Article},
	abstract = {We describe an integral equation method for obtaining the distribution of a nematic fluid near a wall and interacting with a uniform orienting field. Complete density-orientational profiles are calculated for a model nematic with different wall-particle interactions and different orientations of the wall with respect to the field. For orienting walls we identify particular long-range correlations that are responsible for reorientation of the bulk nematic at zero external field. These correlations become stronger as the wall-particle interaction is increased in range; they become longer ranged as the orienting field is weakened. Special attention is focused on systems where the wall-particle interaction favors orientations perpendicular to the surface. The local director orientation can vary discontinuously with the distance from the surface when the orienting influences of the field and the wall are antagonistic. At high densities smectic-like structures appear. Adsorption phenomena are also discussed. For inert hard walls, the ordered fluid avoids the surface, and a surface layer where the particles tend to orient perpendicular to the bulk director appears. Experimentally, this might be seen as wetting of the wall by a less-ordered fluid. (C) 2005 American Institute of Physics.},
	keywords = {ALIGNMENT, APPROXIMATION, LIQUID-CRYSTALS, MODEL, ORNSTEIN-ZERNIKE EQUATION, PHASE-TRANSITION, SOLID SUBSTRATE, SUBSTRATE INTERFACE, SURFACE},
	isbn = {0021-9606},
	url = {<Go to ISI>://000226748800030},
	author = {Sokolovska, T. G. and Sokolovskii, R. O. and Patey, G. N.}
}
@article {988,
	title = {Surface-induced ordering of nematics in an external field: The strong influence of tilted walls},
	journal = {Physical Review Letters},
	volume = {92},
	number = {18},
	year = {2004},
	note = {ISI Document Delivery No.: 818XNTimes Cited: 8Cited Reference Count: 19},
	month = {May},
	pages = {4},
	type = {Article},
	abstract = {Microscopic theory is used to investigate surface-induced order in a model nematic subjected to an external orienting field. The wall-particle interaction tends to orient particles perpendicular to the surface. It is shown that if the wall is tilted at similar to45degrees to the field, the reorientational effects can be an order of magnitude larger than those observed for perpendicular or parallel orientations. The surprising observation is associated with the breaking of a particular bulk symmetry. A possible practical application of the tilted geometry is briefly discussed.},
	keywords = {CONTACT, FLUID, LIQUID-CRYSTALS, ORNSTEIN-ZERNIKE EQUATION, PHASE, SUBSTRATE, TRANSITIONS},
	isbn = {0031-9007},
	url = {<Go to ISI>://000221277900033},
	author = {Sokolovska, T. G. and Sokolovskii, R. O. and Patey, G. N.}
}
@article {3801,
	title = {Monte Carlo simulations of orientational ordering of solutes in a nematic solvent: Comparison with mean-field models},
	journal = {Molecular Physics},
	volume = {88},
	number = {3},
	year = {1996},
	note = {ISI Document Delivery No.: UT951Times Cited: 16Cited Reference Count: 23},
	month = {Jun},
	pages = {767-782},
	type = {Article},
	abstract = {Monte Carlo simulations were used to study orientational ordering of solutes in a nematic phase. Nematogens were modelled as hard prolate ellipsoids with an axis ratio of 5:1. Solutes were also modelled as hard prolate ellipsoids, with a variety of sizes and shape anisotropies. Solute order parameters and singlet orientational distribution functions were analysed using several mean-field models. The results confirm that these empirical mean-field potentials are closely linked to the anisotropic short-range repulsive forces that are crucial for the formation of the nematic phase.},
	keywords = {ANISOTROPIC SYSTEMS, COMPUTER-SIMULATION, ELECTRIC-DIPOLE INTERACTIONS, LIQUID-CRYSTALS, MOLECULES, NEMATOGEN, PHASE, POTENTIALS, SIZE},
	isbn = {0026-8976},
	url = {<Go to ISI>://A1996UT95100015},
	author = {Polson, J. M. and Burnell, E. E.}
}
@article {2920,
	title = {THE ORIENTATION OF MOLECULES WITH INTERNAL-ROTATION IN NEMATIC PHASES},
	journal = {Molecular Physics},
	volume = {80},
	number = {1},
	year = {1993},
	note = {ISI Document Delivery No.: LW723Times Cited: 10Cited Reference Count: 33},
	month = {Sep},
	pages = {177-189},
	type = {Article},
	abstract = {The anisotropic couplings obtained from the H-1 nuclear magnetic resonance (NMR) spectra of partially oriented molecules with internal rotation are difficult to analyse because the order parameters for each conformer cannot be deduced without assumptions. The purpose of this paper is to show how a model for the anisotropic short-range potential can be useful in the interpretation of the high-resolution H-1 NMR spectra of the flexible molecules furfural, 2-chlorobenzaldehyde, and 2,2{\textquoteright}-dithiophene dissolved in a 55\% Merck ZLI 1132-45\% N-(p-ethoxybenzylidene)-2,6-dideutero-p{\textquoteright}-n-butylaniline (w/w) mixture. In this nematic mixture there is no contribution to the anisotropic potential from the interaction between the solute molecular quadrupole moment and the average electric field gradient of the liquid crystal solvent; the dominant anisotropic intermolecular potential in this mixture is taken to result solely from short-range interactions. We find good agreement between experiment and the order parameters calculated by the model of short-range interactions. The ratios of order parameters for the s-cis and s-trans conformers predicted by the model are used to calculate the statistical weights of the s-trans conformation for the solutes: at 304 K, p(trans)(furfural) = 0.45 +/- 0.02, p(trans)(2-chlorobenzaldehyde) = 0.901 +/- 0.006 and p(trans)(2,2{\textquoteright}-dithiophene) = 0.6094 +/- 0.0008.},
	keywords = {BARRIER, CONFORMATION, LIQUID-CRYSTALS, ORDER, SIZE, SOLUTES},
	isbn = {0026-8976},
	url = {<Go to ISI>://A1993LW72300013},
	author = {ter Beek, L. C. and Zimmerman, D. S. and Burnell, E. E.}
}
@article {2860,
	title = {ORIENTATIONAL ORDER OF PLANAR SOLUTES IN A ZERO AVERAGE ELECTRIC-FIELD GRADIENT NEMATIC ENVIRONMENT},
	journal = {Molecular Physics},
	volume = {78},
	number = {3},
	year = {1993},
	note = {ISI Document Delivery No.: KQ355Times Cited: 6Cited Reference Count: 31},
	month = {Feb},
	pages = {673-685},
	type = {Article},
	abstract = {The order matrices for 19 dihalobenzenes of C(s) and C2v symmetry have been measured using the NMR spectra of these molecules as solutes in the nematic mixture of 55 wt\% Merck ZLI-1132 and 45 wt\% N-(4-ethoxybenzylidene)-2,6-dideutero-4{\textquoteright}-n-butylaniline. In this liquid crystal, the contribution to the orientational potential from the interaction between the molecular quadrupole moment and the mean electric field gradient of the liquid crystal can be neglected. The results are compared with predictions of a model which describes the anisotropic intermolecular potential in terms of (1) an elastic distortion of the liquid crystal and (2) an anisotropic surface interaction between solute and liquid crystal. Not only are the largest (in magnitude) order parameters very well fitted, but also the calculated anisotropies in the order matrices agree with the experimental ones. It is demonstrated that the results cannot be fitted with a bond-additive approach.},
	keywords = {HYDROGEN, LIQUID-CRYSTALS, NMR, SIZE},
	isbn = {0026-8976},
	url = {<Go to ISI>://A1993KQ35500010},
	author = {Li, K. Y. Z. and Zimmerman, D. S. and Burnell, E. E.}
}
@article {7119,
	title = {THE CONFORMATION OF 2,2{\textquoteright}-DITHIOPHENE IN NEMATIC SOLVENTS DETERMINED BY H-1-NMR},
	journal = {Molecular Physics},
	volume = {74},
	number = {5},
	year = {1991},
	note = {ISI Document Delivery No.: GY085Times Cited: 24Cited Reference Count: 26},
	month = {Dec},
	pages = {1027-1035},
	type = {Article},
	abstract = {In this paper we report a determination of the structure 2,2{\textquoteright}-dithiophene dissolved in different nematic liquid crystal solvents. The H-1-NMR spectra of this molecule dissolved in a 55\% Merck ZLI 1132/45\% N-(4-ethoxybenzylidene)-4{\textquoteright}-n-butylaniline (w/w) mixture are recorded at 300 and 304 K and are analysed. The dipolar coupling constants obtained are used to show that the solute molecule exists in both the s-cis and the s-trans conformations. The s-trans conformer is planar and the absolute value of the dihedral angle-PHI between the two thiophene ring planes for the s-cis conformer is found to be (24 +/- 1)degrees. Using the same method of analysis we reinterpreted two additional independent sets of published dipolar coupling constants from H-1-NMR spectra of 2,2{\textquoteright}-dithiophene dissolved in Merck Phase IV at room temperature and in 80\% N-(4-ethoxybenzylidene)-4{\textquoteright}-n-butylaniline/20\% O-carbobutoxy-4-oxybenzoic acid ethoxy phenyl ester at 301 K. These additional studies yield the same results for the structure of 2,2{\textquoteright}-dithiophene. We also estimate that in each of the three nematic solvents (61 +/- 3)\% of the solute 2,2{\textquoteright}-dithiophene exists in the s-trans state.},
	keywords = {2, 2{\textquoteright}-BITHIENYL, BARRIER, LIQUID-CRYSTALS, MOLECULES, orientational order, PHASE, SIZE, SOLUTES},
	isbn = {0026-8976},
	url = {<Go to ISI>://A1991GY08500007},
	author = {ter Beek, L. C. and Zimmerman, D. S. and Burnell, E. E.}
}
