Gay-Berne

Berardi R, Emerson A P J, Smith W and Zannoni C 1993 Monte Carlo investigations of a Gay-Berne liquid crystal J. Chem. See. Faraday Trans. 89 4069-78... 

Allen M P, Warren M A, Wilson M R, Sauron A and Wiliam S 1996 Molecular dynamics calculation of elastic constants in Gay-Berne nematic liquid crystals J. Chem. Phys. 105 2850-8... 

Bates M A and Luckhurst G R 1996 Computer simulation studies of anisotropic systems. 26. Monte Carlo investigations of a Gay-Berne discotic at constant pressure J. Chem. Phys. 104 6696-709... 

Wilson M R 1997 Molecular dynamics simulations of flexible liquid crystal molecules using a Gay-Berne/Lennard-Jones model J. Chem. Phys. 107 8654-63... 

I)(. p end ing upon the parameters chosen, simulations performed using the Gay-Berne potential show behaviour typical of liquid crystaUine materials. Moreover, by modifying the potential, 111. can determine what contributions affect the liquid crystalline properties and so help to suggest what types of molecule should be made in order to attain certain properties. 

Kurst G R, R A Stephens and R W Phippen 1990. Computer Simulation Studies of Anisotropic iystems XIX. Mesophases Formed by the Gay-Berne Model Mesogen. Liquid Crystals 8 451-464. e F J, F Has and M Orozco 1990. Comparative Study of the Molecular Electrostatic Potential Ibtained from Different Wavefunctions - Reliability of the Semi-Empirical MNDO Wavefunction. oumal of Computational Chemistry 11 416-430. 

FIG. 7 Same as Fig. 5, but for a nematic Gay-Berne film confined between homeotropically anchoring substrates (from Ref. 48). 

T. Gruhn, M. Schoen. A grand canonical ensemble Monte Carlo study of confined planar and homeotropically anchored Gay-Berne films. Mol Phys 95 681-692, 1998. 

One prominent example of rods with a soft interaction is Gay-Berne particles. Recently, elastic properties were calculated [89,90]. Using the classical Car-Parrinello scheme, the interactions between charged rods have been considered [91]. Concerning phase transitions, the sohd-fluid equihbria for hard dumbbells that interact additionally with a quadrupolar force was considered [92], as was the nematic-isotropic transition in a fluid of dipolar hard spherocylinders [93]. The influence of an additional attraction on the phase behavior of hard spherocylinders was considered by Bolhuis et al. [94]. The gelation transition typical for clays was found in a system of infinitely thin disks carrying point quadrupoles [95,96]. In confined hquid-crystalline films tilted molecular layers form near each wall [97]. Chakrabarti has found simulation evidence of critical behavior of the isotropic-nematic phase transition in a porous medium [98]. 

In simple single-site liquid crystal models, such as hard-ellipsoids or the Gay-Berne potential, a number of elegant techniques have been devised to calculate key bulk properties which are useful for display applications. These include elastic constants for nematic systems [87, 88]. However, these techniques are dependent on large systems and long runs, and (at the present time) limitations in computer time prevent the extension of these methods to fully atomistic models. 

Fig. 7. Snapshots from a smectic-A phase of liquid crystal dimer molecules composed of two Gay-Berne mesogens linked by a flexible alkyl chain. Data from [112] supplied by Dr M R Wilson, University of Durham...

Wilson MR (1996) GBMOL, a molecular dynamics package for modeling systems composed of Lennard-Jones and Gay-Berne particles... 

Computer Simulation of Liquid Crystal Phases Formed by Gay-Berne Mesogens... 

Keywords liquid crystals, Gay-Berne, computer simulations, phase structure... 

Sect. 12 we describe the results of simulations of Gay-Berne molecules at interfaces and in confined geometries. 

The creation of the Gay-Berne potential owes much to the original work by Corner in his pioneering development of pair potentials for molecules [7]. He had noted that the Lennard-Jones 12-6 potential provided a good description of the interactions between atoms... 

Here, k provides a measure of the anisotropy in the well depth and for rodlike molecules is the ratio 8 1 where and Eg are the well depths when the molecules are side-by-side and end-to-end, respectively. The scaling parameter Eq is the well depth when the molecules are in the cross configuration as we can see by setting u, uj = u, f = uj f = 0 in Eqs. (4), (6) and (7). We should note that in the limit k and k tend to unity, that is x and x vanish then the Gay-Berne potential is reduced to the Leonard-Jones 12-6 potential. 

The Gay-Berne potential depends on four parameters in its scaled form, that is U(uiUjr)/eo as a function of the scaled distance r/Uoi these parameters are k. 

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