  Considering the nuclear motion, the authors give out the nonrelativistic
ground energy of a helium atom by using a simple but effective variational wave
function with a flexible parameter $k$. Based on this result, the relativistic
and radiative corrections to the nonrelativistic Hamiltonian are discussed. The
high precision value of the helium ground energy is evaluated to be -2.90338
a.u., and the relative error is 0.00034%.
