Toward a quasiphase transition in the single-file chain of water molecules: Simple lattice model.

Recently, Ma et al. [Phys. Rev.

Regularly alternating spin-1/2 anisotropic XY chains: the ground-state and thermodynamic properties.

Using the Jordan-Wigner transformation and continued fractions we calculate rigorously the thermodynamic quantities for the spin-1/2 transverse Ising chain with periodically varying intersite interactions and/or on-site fields. We consider in detail the properties of the chains having a period of the transverse field modulation equal to 3. The regularly alternating transverse Ising chain exhibits several quantum phase transition points, where the number of transition points for a given period of alternation strongly depends on the specific set of the Hamiltonian parameters.