Quantum induced w = -1 crossing of the quintessence and phantom models
  Considering the single scalar field models of dark energy, i.e. the quintessence and phantom models, it is shown that the quantum effects can cause the system crosses the w = -1 line. This phenomenon does not occur in classical level. The quantum effects are described via the account of conformal anomaly. 
M. Alimohammadi and L. Sadeghian