What is Gromacs?
From http://gromacs.org :
GROMACS is a versatile package to perform molecular dynamics, i.e. simulate the Newtonian equations of motion for systems with hundreds to millions of particles.
It is primarily designed for biochemical molecules like proteins, lipids and nucleic acids that have a lot of complicated bonded interactions, but since GROMACS is extremely fast at calculating the nonbonded interactions (that usually dominate simulations) many groups are also using it for research on non-biological systems, e.g. polymers.
Install pre-compiled package
sudo apt install gromacs
Optionally, install gropacs-mpich package for parallel support:
sudo apt install gromacs-mpich
Install from the source
If you need to make Gromacs takes full advantage of your system, such as your commercial compiler, Math Library, GPU, and parallelization options you may choose to install from the source.
Here is the instruction on the current latest version of GROMACS:
Gromacs is a Molecular Dynamics simulation package that involves significant physics, math, and computer science. The manual is quite comprehensive in covering all these topics. So start with reading reference manual corresponding to your version of Gromacs.
Learning Gromacs by examples
You can also learn from examples provided by Professor Lemkul: