Just catching up.
NWChem 6.8 is now available on Github https://github.com/nwchemgit/nwchem.
NWChem provides many methods for computing the properties of molecular and periodic systems using standard quantum mechanical descriptions of the electronic wavefunction or density. Its classical molecular dynamics capabilities provide for the simulation of macromolecules and solutions, including the computation of free energies using a variety of force fields. These approaches may be combined to perform mixed quantum-mechanics and molecular-mechanics simulations.
Instructions for compiling NWChem on various platforms including Mac OSX https://github.com/nwchemgit/nwchem/wiki/Compiling-NWChem.