  Adaptive resolution schemes allow the simulation of a molecular fluid
treating simultaneously different subregions of the system at different levels
of resolution. In this work we present a new scheme formulated in terms of a
global Hamiltonian. Within this approach equilibrium states corresponding to
well defined statistical ensembles can be generated making use of all standard
Molecular Dynamics or Monte Carlo methods. Models at different resolutions can
thus be coupled, and thermodynamic equilibrium can be modulated keeping each
region at desired pressure or density without disrupting the Hamiltonian
framework.
