Amber is a suite of biomolecular simulation programs. It began in the late 1970's, and is maintained by an active develpment community

Amber 18 ajor new features include:

• Free energy calculations on GPUs
• GPU support for 12-6-4 ion potentials
• Domain decomposition for CPU-parallelism
• Nudged elastic band calculations for pmemd (CPU and partial GPU implementation)
• Constant redox potential calculations, to supplement constant pH simulations
• Support and significant performance improvements for the latest Maxwell, Pascal and Volta GPUs from NVIDIA.
• New pmemd.gem code for advanced force fields, including AMOEB

AmberTools 18 new features include

• CUDA-enabled pbsa solver; extensions for membrane modeling with PB *lambda-dynamics method for constant pH simulations *packmol_memgen tool for building lipids and bilayers *New ("middle") integration algorithms in sander *Build tools based on CMake *Continued updates and extensions to cpptraj: *ability to obtain energies from snapshots of PME simulations *Pairlist and other speedups *improved scripting abilities

Instructions for installing Amber under Mac OSX are here http://ambermd.org/Installation.php

You will need to install gfortran, whilst you can download the binary it might be worth considering using Homebrew as described here