Guo, ZK (reprint author), CCAST, World Lab, POB 8730, Beijing 100080, Peoples R China.
We investigate in this Letter the cosmological evolution of a dark energy model with two scalar fields where one of the scalar has canonical kinetic energy and another scalar has negative kinetic energy term. For such a system with exponential potentials we find that during the evolution of the universe the equation of state w changes from w greater than or equal to -1 to w < -1, which is consistent with the recent observations. A phase-plane analysis shows that the "phantom"-dominated scaling solution is the stable late-time attractor of this type of models. (C) 2005 Elsevier B.V. All rights reserved.