Amber is a free-as-in-freedom molecular dynamics toolkit. Until now,

there was no homebrew distribution of Amber. Because most serious
molecular dynamics simuations are done on cluster computers
rather than macbooks, one might ask 'why bother?'. Having amber on
one's own machine is useful for prototyping something simple in an
environment where one has full control over the environment and
guaranteed access. Scientists might want to try out some simple things
without bothering with the many configuration options. With this in
mind, the installation with default options is simple and conservative.