Critical exponent for semilinear wave equation with critical potential

We consider the Cauchy problem for the semilinear wave equation ${u_{tt} - \Delta u + V(x)u_t = |u|^p}$ .When ${V(x) = V_0(1 + |x|^2)^{-1/2}, V_0 \geq n}$ , we prove that the critical exponent for the problem is ${p_c(n)=\left\{\begin{array}{ll} 1+\frac{2}{n-1},& n \geq 2,\ +\infty,& n=1. \end{array}\right.}$