  Nowadays, there is pressing demand for sustainable energy sources, or clean
and 'green' fuel and hydrogen is a perfect candidate. It can be made by
dissociating methane with the energy input compensated by metal-hydrogen bond
formation. Industry uses Nickel supported on $\gamma$-alumina for this
rate-limiting step.
  This work shows how to use Quantum Monte Carlo calculations to take
(user-guided) information summarising chemistry of heterogeneous catalysis from
a generic Jastrow factor, that allows electron correlation to be included in
the density. This, in turn, gives accurate values of properties, in particular
the activation barrier for stretching one methane C-H bond, before adsorbing
CH3- and H- on vicinal nickel atoms in the close-packed (111) plane.
  The CH3- co-ordinates to a hollow site defined by three Ni atoms and, new to
this work, another Ni-atom co-ordinates the H-atom from the dissociation.
