Finite-size-scaling study of a generalized quantumhard-rod model in a longitudinal magnetic field

The critical behaviour of a one-dimensional generalized quantum hard-rods model in a longitudinal magnetic field is studied by finite-size scaling using the Lanczos algorithm. The maximal lattice in our calculation is L=20. For m mc (mc=3), the transition becomes first order and for m 4 new types of phases appear. The ground-state properties are studied. The phase diagrams for m=2,3 and 4 are obtained. Finally, for m 3 a reentrant phenomenon is located.