Renormalization algorithms for Quantum-Many Body Systems in two and   higher dimensions
  We describe quantum many--body systems in terms of projected entangled--pair states, which naturally extend matrix product states to two and more dimensions. We present an algorithm to determine correlation functions in an efficient way. We use this result to build powerful numerical simulation techniques to describe the ground state, finite temperature, and evolution of spin systems in two and higher dimensions. 
F. Verstraete, J. I. Cirac