Phase field modeling has emerged as a powerful tool in crystal growth simulation, but the description of the anisotropic function for three-dimensional (3D) interfacial free energy without miss-orientation remains quite difficult, especially for the multi-crystalline cases. In this paper, a simple function for keeping the convexity in the reciprocal surface free energy is proposed, and the simulated equilibrium shapes are in good agreement with the analytical ones. Some examples on the dendritic growth in a supercooled melt for mono- and multi-crystalline crystals are also illustrated. (C) 2012 Elsevier B.V. All rights reserved.