The official release of GROMACS 2018 is now available.
What new things can you expect? Please see the release notes highlights at http://manual.gromacs.org/documentation/2018/release-notes/index.html.
You can find the code, manual, release notes, installation instructions and test suite at the links below.
Documentation: http://manual.gromacs.org/documentation/2018/index.html (includes install guide, user guide, reference manual, and release notes)