# Error in pdb2gmx command **URL:** \ **Category:** User discussions\ **Tags:** pdb2gmx\ **Created:** [February 25, 2023, 6:56am UTC](https://gromacs.bioexcel.eu/t/error-in-pdb2gmx-command/5871 "2023-02-25T06:56:59Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\ **Post date:** [February 25, 2023, 6:55pm UTC](https://gromacs.bioexcel.eu/t/error-in-pdb2gmx-command/5871/3 "2023-02-25T18:55:38Z")
Just for posterity, your problem was not with atom **types** but with atom **names**. These are two different concepts, since atom type is a force field parameter concept related to LJ terms. For SPC/E, look in the `spce.itp` file: ```auto [atoms] ; nr type resnr residue atom cgnr charge mass 1 OWSPCE 1 SOL OW 1 -0.8476 2 HWSPCE 1 SOL HW1 1 0.4238 3 HWSPCE 1 SOL HW2 1 0.4238 ``` Although we provide this topology if users want to try it, I would strongly urge you to use the validated water model for use with CHARMM36, which is the CHARMM-modified TIP3P (the default in `tip3p.itp` that we distribute with the CHARMM force field). Use of SPC/E is essentially untested and you run the risk of invalid simulations. --- _[View the full topic](https://gromacs.bioexcel.eu/t/error-in-pdb2gmx-command/5871)._