  We perform quantum Monte Carlo (QMC) calculations to determine minimum energy
pathways of simple chemical reactions, and compare the computed geometries and
reaction barriers with those obtained with density functional theory (DFT) and
quantum chemistry methods. We find that QMC performs in general significantly
better than DFT, being also able to treat cases in which DFT is inaccurate or
even unable to locate the transition state. Since the wave function form
employed here is particularly simple and can be transferred to larger systems,
we suggest that a QMC approach is both viable and useful for reactions
difficult to address by DFT and system sizes too large for high level quantum
chemistry methods.
