Modify GROMACS after installation

User discussions
1

GROMACS version: 2023.3
GROMACS modification: No

I just installed GROMACS on my laptop using the “quick and dirty” installation pathway. Unfortunately, I just realized that I explicitly had to indicate that I want to use my GPU for simulations during the installation process. Is there any possibility to modify GROMACS afterwards? Thanks in advance!

2

Hi!

There is not way to “modify” GROMACS installation, but building GROMACS anew (with GPU enabled) and installing it would work. There is usually no need to uninstall the old version before.

3

Thank you very much!

4

There still might be a misunderstanding form my side: In the installation documentation there are two options that I can’t really tell the difference between, because I am not really into the topic (yet):

-DGMX_MPI=on

and

-DGMX_GPU=CUDA

I want to use the GPU on my laptop (NVIDIA GeForce RTX 3060 Laptop GPU), so do I have to use both options? Under the “GPU-aware MPI support” heading in the docs, there is talk about “simulations using multiple GPUs”, but I just want to use one GPU, namely the one mentioned before. So do I need the cuda toolkit and openmpi? Thanks!

5

If you intend to use one GPU, you do not need an external MPI library.

1 Like
6

These two options are completely orthogonal.

  • CUDA is a library for working with NVIDIA GPUs. You need CUDA to use your GPU.

  • MPI is a library for parallelizing over multiple computers (can be used on a single machine too). As @jalemkul said, you don’t need GMX_MPI=ON for a typical laptop build, and you don’t need to have OpenMPI installed.

    • Note: You might benefit from GMX_THREAD_MPI=ON (which is a separate thing from GMX_MPI!). But it is enabled by default, no extra flags needed.