  We introduce an efficient scheme for the molecular dynamics of electronic
systems by means of quantum Monte Carlo. The evaluation of the
(Born-Oppenheimer) forces acting on the ionic positions is achieved by two main
ingredients: i) the forces are computed with finite and small variance, which
allows the simulation of a a large number of atoms, ii) the statistical noise
corresponding to the forces is used to drive the dynamics at finite temperature
by means of an appropriate friction matrix. A first application to the
high-density phase of Hydrogen is given, supporting the stability of the liquid
phase at = 300GP a and = 400K.
