Quantum phase transition in a transverse Ising chain with regularly   varying parameters
  Using rigorous analytical analysis and exact numerical data for the spin-1/2 transverse Ising chain we discuss the effects of regular alternation of the Hamiltonian parameters on the quantum phase transition inherent in the model. 
O.Derzhko, J.Richter, T.Krokhmalskii, O.Zaburannyi