title: Boundary conditions and variable ground state entropy for the antiferromagnetic Ising model on a triangular lattice.
abstract: The ground state entropy density of the antiferromagnetic Ising model on a triangular lattice is considered in the infinite volume limit as a function of boundary conditions on a finite triangular domain. The ground states of this domain do not map to a dimer covering and so cannot be classified into string sectors. A parametrized boundary condition is identified that allows the entropy density to be tuned to values between nondegeneracy and maximal degeneracy. The results are compared to those for a rectangular periodic domain for which the ground states can be classified into string sectors.
authors.affiliation: Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. rick@elec.canterbury.ac.nz
authors.forename: R P
authors.initials: RP
authors.lastname: Millane
authors.forename: N D
authors.initials: ND
authors.lastname: Blakeley