  An appropriate iterative scheme for the minimization of the energy, based on
the variational Monte Carlo (VMC) technique, is introduced and compared with
existing stochastic schemes. We test the various methods for the 1D Heisenberg
ring and the 2D t-J model and show that, with the present scheme, very accurate
and efficient calculations are possible, even for several variational
parameters. Indeed, by using a very efficient statistical evaluation of the
first and the second energy derivatives, it is possible to define a very
rapidly converging iterative scheme that, within VMC, is much more convenient
than the standard Newton method. It is also shown how to optimize
simultaneously both the Jastrow and the determinantal part of the wave
function.
