The empirical valence bond (EVB) approach proposed by Chang and Miller [J. Phys. Chem. 94, 5884 (1990)] for constructing global potential energy surfaces has the potential for treating large molecular systems. In this work, we slightly modify the expression of Chang and Miller by adding a damping function along the reaction coordinate to ensure the proper asymptotic behavior of the potential. We apply the EVB method to describe the cis-trans isomerization in HONO, and compute the isomerization rates in the low-energy tunneling regime by employing the semiclassical method that treats tunneling within classical trajectory calculations. (C) 2003 American Institute of Physics.