GROMACS version: 2109
GROMACS modification: Yes/No
I want to use the LJ12-4, LJ12-9 and LJ12-6 potential parameters for different components of my system. Can we use the LJ12-4 and LJ12-9 potential functions in Gromacs, if so how should we include the parameters in the itp file? (I see that the gmx sigeps only converts C6/Cn to sigma and epsilon and vice versa).
The non-bonded potentials that are currently implemented in GROMACS are LJ 12-6 and Buckingham (see http://manual.gromacs.org/current/reference-manual/functions/nonbonded-interactions.html?highlight=potential). For LJ12-9 and LJ12-4 potentials you can use tabulated potentials (note you need a tabulated potential for type of pair since you can not use combination rule), but the functionality (tabulated potential) has been removed in version 2019 and 2020 (but not 2018), the plan is to have it back as soon as possible in one of following release.