Understanding the struct t_iparams from GROMACS codebase

GROMACS version: 2024.1
GROMACS modification: No

Hi, I am going through the codebase and found this t_iparams which holds the force parameters. Now, when I am running the MD simulation with 23558 atoms, I want to extract the LJ Parameters from this vector of struct t_iparams ‘’‘topGlobal_.ffparams.iparams’‘’. But the length of the vector is 110 only. So, is where the actual parameters stored or is it some kind of a map?


The number of LJ parameters is equal to the number of atom type pairs, not the number of atoms. The function makeNonBondedParameterLists() extract the LJ parameters, have a look there.

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It is there. Thanks a lot @hess.