A new potential energy surface is proposed for the ground electronic state of LiH2 and the quantum wave packet calculation for LiH + H reaction is performed. The full configuration interaction method and an aug-cc-pVQZ basis set are employed to calculate the potential energy for a set of criteriously selected geometries. The many-body expansion procedure is used to describe the analytical PES function. The new PES leads to a very different wave packet dynamics for both exothermic (Li + H-2) and thermoneutral (H + LiH) reactions when compared with the previous ones. (C) 2009 Elsevier B. V. All rights reserved.