  We report results of both the Diffusion Quantum Monte Carlo (DMC) and
Reptation Quantum Monte Carlo (RMC) methods on the potential energy curve of
the helium dimer. We show that it is possible to obtain a highly accurate
description of the helium dimer. An improved stochastic reconfiguration
technique is employed to optimize the many-body wave function, which is the
starting point for highly accurate simulations based on the Diffusion Quantum
Monte Carlo (DMC) and Reptation Quantum Monte Carlo (RMC) methods. We find that
the results of these methods are in excellent agreement with the best
theoretical results at short range, especially the recently developed Reptation
Quantum Monte Carlo (RMC) method, yield particularly accurate results with
reduced statistical error, which gives very excellent agreement across the
whole potential curve. For the equilibrium internuclear distance of 5.6 bohr,
the calculated total energy with Reptation Quantum Monte Carlo (RMC) method is
-5.807483599$\pm$0.000000016 hartrees and the corresponding well depth is
-11.003$\pm$0.005 K.
