Onsager's spherocylinders revisited

Since the work of Onsager, systems of hard spherocylinders have played a special role as the theoretician’s “ideal” nematic liquid crystals. It is, however, well-known that the Onsager theory is only a good description for extremely nonspherical particles. A quantitative measure for the range of validity of this theory is obtained from direct numerical calculation of the third through fifth virial coefficients of hard spherocylinders with length-to-width ratios, LID, between 1 and lo6. The phase diagram of spherocylinders with “realistic” LID ratios can only be obtained by computer simulation. We report molecular dynamics and Monte Carlo simulations for spherocylinders with LID = 5. These calculations suggest that the oldest model for a hard-core nematic may, in fact, have a smectic liquid-crygalline phase as well. Includes an erratum, published in vol; 92; issue 18, 1988, - p. 5314