  Applying a variational Monte Carlo method to a two-dimensional t-J model, we
study the nonmonotonic d_{x^2-y^2}-wave superconductivity, observed by Raman
scattering and ARPES experiments in the electron-doped cuprates. As a gap
function in the trial state, we extend the d-wave form (ext.d) so as to have
its maxima located near the hot spots of the system. It is found that, in
contrast to the hole-doped case, the ext.d wave is always more stable than the
simple d wave in the electron-doped case, and the magnetic correlation of the
wave vector (\pi,\pi) as well as the pair correlation is enhanced. These
results corroborate spin-correlation-mediated superconductivity in cuprates,
recently argued from a FLEX calculation. In addition, we confirm that s- and
p-wave symmetries are never stabilized even in the over-doped regime.
