PRESENCE OF RACEMIC PHASES AT LOW-TEMPERATURES IN A 3-DIMENSIONAL LATTICE-GAS OF ENANTIOMERS

A lattice gas on the body-centred cubic lattice containing a pair of e nantiomers is studied for a domain of orientation-dependent interactio ns in which the ground-state configurations are infinitely degenerate, each containing a racemic mixture of enantiomers. A finite number of these configurations are dominant, meaning they have a maximum number of lowest-energy excitations. An extension of the PirogovSinai theory of phase transitions due to Bricmont and Slawny is used to showthat th e low-temperature phases for this domain of interactions have the stru cture of the dominant ground-state configurations, together with a num ber of defects or excitations. This is the first proof of the existenc e of racemic phases at Tow temperatures in a lattice model.