# No such molecule type LIG **URL:** \ **Category:** User discussions\ **Created:** [February 16, 2023, 10:25pm UTC](https://gromacs.bioexcel.eu/t/no-such-molecule-type-lig/5819 "2023-02-16T22:25:44Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![sanze](https://avatars.discourse-cdn.com/v4/letter/s/779978/32.png) [@sanze](https://gromacs.bioexcel.eu/u/sanze)\ **Post date:** [February 16, 2023, 10:25pm UTC](https://gromacs.bioexcel.eu/t/no-such-molecule-type-lig/5819/1 "2023-02-16T22:25:45Z")
GROMACS version: 2023 GROMACS modification: Yes/No In wsl (Ubuntu), I installed the new Gromacs v2023 version. It successfully runs the simulation of proteins in water, but when I run the simulation of the protein-ligand complex. It generates some errors. The common error is No such molecule type LIG. In the molecule section, I define the LIG. [molecules] ; Compound #mols Protein\_chain\_A 1 LIG 1 SOL 23527 ERROR 1 [file topol.top, line 8889]: No such moleculetype LIG The .gro and .itp have same name LIG cmd: gmx grompp -f ions.mdp -c solv.gro -p topol.top -o ions.tpr Example… LIG.gro created by acpype (v: 2022.7.21) 29 1 LIG C 1 -0.263 0.071 -0.001 1 LIG C1 2 -0.264 -0.070 0.003 1 LIG C2 3 -0.145 -0.143 0.003 1 LIG C3 4 -0.028 -0.071 -0.002 1 LIG C4 5 -0.027 0.067 -0.004 1 LIG C5 6 -0.143 0.142 -0.003 1 LIG C6 7 0.113 0.109 -0.008 1 LIG O 8 0.152 0.224 0.001 1 LIG N 9 0.188 -0.005 -0.015 1 LIG C7 10 0.111 -0.118 -0.006 Did I miss something? Please help me. Thanks in advance ---
**Author:** ![avilla](https://avatars.discourse-cdn.com/v4/letter/a/f1d935/32.png) [@avilla](https://gromacs.bioexcel.eu/u/avilla)\ **Post date:** [February 17, 2023, 1:14pm UTC](https://gromacs.bioexcel.eu/t/no-such-molecule-type-lig/5819/2 "2023-02-17T13:14:46Z")
Hi, Do you get the error when you run gmx grompp? Then, it looks like that program do not find the parameter information for the LIG in the topology file (and in all the file included in the topol.top). You can check if you provide such a information. \Alessandra ---
**Author:** ![faaiza](https://avatars.discourse-cdn.com/v4/letter/f/df788c/32.png) [@faaiza](https://gromacs.bioexcel.eu/u/faaiza)\ **Post date:** [July 18, 2023, 7:39pm UTC](https://gromacs.bioexcel.eu/t/no-such-molecule-type-lig/5819/3 "2023-07-18T19:39:41Z")
hi, were you able to solve this? ---
**Author:** ![sanze](https://avatars.discourse-cdn.com/v4/letter/s/779978/32.png) [@sanze](https://gromacs.bioexcel.eu/u/sanze)\ **Post date:** [July 18, 2023, 8:51pm UTC](https://gromacs.bioexcel.eu/t/no-such-molecule-type-lig/5819/4 "2023-07-18T20:51:43Z")
Yes. I solved by correcting the file name. Actually i was using acpype for ligand topology. Acpype generate the file name by your file name and inside the file in header section it also includes original file name with extension. such as my file name is lig.pdb so it include it as lig.pdb.gro or lig.pdb.mol2.gro or lig.pdb.mol2.itp. You can check your ligand topology header line and in itp check both sections: atomtypes and molecules type. Name should be same everywhere. For example. your molecule topology file name is lig.gro and lig.itp and atom coordinates name also a LIG then in every file, it should be a lig or LIG. And also check the same in nvt.mdp, npt.mdp and md.mdp.