In the framework of a single scalar field quintom model with higher derivative , we construct in this paper a dark energy model of which the equation of state ( EOS ) w crosses over the cosmological constant boundary .
Interestingly during the evolution of the universe w < -1 happens just for a period of time with a distinguished feature that w starts with a value above -1 , transits into w < -1 , then comes back to w > -1 .
This avoids the Big Rip jeopardy induced by w < -1 .