@article {5104,
title = {Ferroelectric order in positionally frozen dipolar systems},
journal = {Journal of Chemical Physics},
volume = {115},
number = {10},
year = {2001},
note = {ISI Document Delivery No.: 466LTTimes Cited: 13Cited Reference Count: 46},
month = {Sep},
pages = {4718-4731},
type = {Article},
abstract = {We discuss the possibility of long-range ferroelectric order in an amorphous dipolar system. Our model consists of spheres with frozen positions and freely rotating three-dimensional dipole moments. Correlation functions are calculated by means of the hypernetted-chain integral theory combined with the replica method. Our results suggest that inhomogeneities in the frozen spatial structure induce a gradual local freezing of the dipole axes upon decreasing temperature. However, at sufficiently high densities and dipole moments, the long-range interactions dominate the short-range frustration, resulting in a ferroelectric transition. The estimated transition temperatures depend strongly on the degree of spatial correlation in the underlying system of frozen spheres. For a randomly frozen system, we find that the transition temperature is considerably lower than that predicted by mean field theory, and also lower than the temperature where simulations indicate the onset of glass-like behavior. Strong positional correlations can push the transition toward temperatures higher even than those observed for dipolar fluids. (C) 2001 American Institute of Physics.},
keywords = {GROUND-STATE, HARD-SPHERES, HYPERNETTED-CHAIN APPROXIMATION, INTEGRAL-EQUATION THEORY, ISING-MODEL, LIQUID-VAPOR INTERFACE, LOCAL-MEAN-FIELD, orientational order, ORNSTEIN-ZERNIKE APPROXIMATION, RANDOM ANISOTROPY},
isbn = {0021-9606},
url = {://000170647600035},
author = {Klapp, S. H. L. and Patey, G. N.}
}
@article {4848,
title = {Crystallization of dipolar spheres: A discussion of second-order density functional theory},
journal = {Journal of Chemical Physics},
volume = {112},
number = {24},
year = {2000},
note = {ISI Document Delivery No.: 324HYTimes Cited: 6Cited Reference Count: 43},
month = {Jun},
pages = {10949-10956},
type = {Article},
abstract = {We investigate the application of second-order density functional theory to the crystallization of dipolar hard and soft spheres. It is shown that the results are highly sensitive to the repulsive part of the pair potential, and to the symmetry of the fluid phase considered in the density functional theory. In general, the theoretical results for dipolar soft spheres (with r(-12) repulsion) are found to be physically more reasonable than those obtained for dipolar hard spheres. In particular, the fluid-solid density gap is greatly reduced and lies in the range expected on physical grounds and from simulations. However, theories constructed by expanding about the isotropic fluid phase overestimate the stability of the ferroelectric solid for both models, and fail to predict the stable ferroelectric fluids found in computer simulations. We have carried out calculations using ferroelectric dipolar fluids with both perfect and fluctuating orientational order as "starting points" in the density functional expansion. The results demonstrate the high sensitivity of the theory to the underlying fluid state, and strongly indicate the existence of stable ferroelectric fluids in accord with computer simulations. (C) 2000 American Institute of Physics. [S0021-9606(00)50924-6].},
keywords = {FLUIDS, HARD-SPHERES, INTEGRAL-EQUATIONS, LIQUID-VAPOR INTERFACE, NEMATIC PHASE, orientational order, PHASE-TRANSITIONS, SOFT SPHERES, SOLID-PHASES, STABILITY},
isbn = {0021-9606},
url = {://000087617300033},
author = {Klapp, S. H. L. and Patey, G. N.}
}
@article {4849,
title = {Integral equation theory for dipolar hard sphere fluids with fluctuating orientational order},
journal = {Journal of Chemical Physics},
volume = {112},
number = {8},
year = {2000},
note = {ISI Document Delivery No.: 284RDTimes Cited: 21Cited Reference Count: 53},
month = {Feb},
pages = {3832-3844},
type = {Article},
abstract = {We present an integral equation approach to the structural and thermodynamic properties of a fluid of partially aligned dipolar hard spheres. To relate the two-particle correlation functions to the anisotropic singlet density, we mainly employ the Lovett-Mou-Buff-Wertheim equation. We show that, as in the isotropic case, the mean-spherical approximation and the reference hypernetted chain (RHNC) closures lead to quite different results. This is particularly true at high coupling strengths, where the RHNC theory shows a transition from an isotropic to a ferroelectric fluid phase. The predicted transition temperatures are very close to those one obtains from the RHNC theory for the isotropic fluid. (C) 2000 American Institute of Physics. [S0021-9606(00)50707-7].},
keywords = {BOUNDARY-CONDITIONS, COMPUTER-SIMULATION, DENSITY-FUNCTIONAL THEORY, EXTERNAL MAGNETIC-FIELD, HEISENBERG SPIN FLUID, HYPERNETTED-CHAIN APPROXIMATION, LIQUID-VAPOR INTERFACE, NONSPHERICAL PARTICLES, PARALLEL SPHEROCYLINDERS, PERIODIC, PHASE-TRANSITIONS},
isbn = {0021-9606},
url = {://000085345300041},
author = {Klapp, S. H. L. and Patey, G. N.}
}