Quintessence model with double exponential potential

We have reinvestigated the quintessence model with minimally coupled scalar field in the context of recent Supernova observation at z=1.7. By assuming the form of the scale factor which gives both the early time deceleration and late time acceleration, consistent with the observations, we show that one needs a double exponential potential. We have also shown that the equation of state and the behaviour of dark energy density are reasonably consistent with earlier constraints obtained by different authors. This work shows again the importance of double exponential potential for a quintessence field.