Is order of #include important in topol.top file?

User discussions
1

I have just gotten familiarized with the different file types in GROMACS and how they relate to each other for different commands.

I’m wondering if the #include function that is in topol.top file has any restrictions.
If i want to run a protein-ligand MD simulation, i will need to include the ligand.itp in topol.top file.
Does this #include “ligand.itp” need to be placed at a specific position?
What is the rationale for this, if any?

Thanks!

2

After the FF is included, and before the [ molecules ] section.

3

What is the reasoning for having it placed before [ molecules ] section?

4

http://manual.gromacs.org/documentation/current/reference-manual/topologies/topology-file-formats.html

That has the full details on what the topology file .top contains, plus the order.

The file is parsed only once, which implies that no forward references can be treated: items must be defined before they can be used
…
Using [ molecules ] without having used [ system ] before is meaningless and generates a warning.
After [ system ] the only allowed directive is [ molecules ]
…