  We introduce a novel method that combines the accuracy of Quantum Monte Carlo
simulations with ab-initio Molecular Dynamics, in the spirit of Car-Parrinello.
This method is then used for investigating the structure of a two-dimensional
layer of hydrogen at $T=0~\text{K}$ and high densities. We find that
metallization is to be expected at $r_s \approx 1.1$, with an estimated
pressure of $1.0\cdot10^3~a_0~\text{GPa}$, changing from a graphene molecular
lattice to an atomic phase.
