Body
Hello,
Before reporting this as a bug, I would like to understand whether this combination is currently supported by design.
I am using the latest LAMMPS (4Jul2026) together with the ELECTRODE package to simulate a constant-potential supercapacitor.
My system consists of:
-
Carbon electrodes
-
fix electrode/conp
-
kspace_style pppm/electrode
-
pair_style lj/cut/tip4p/long
-
TIP4P water
-
Na⁺ and ClO₄⁻ ions
The simulation aborts immediately with
ERROR: Fix electrode couldn’t find a Coulombic pair style
Before posting here, I searched the documentation, GitHub issues, and previous discussions on the Materials Science Community, but I could not find any discussion specifically about combining the ELECTRODE package with TIP4P water models.
I also spent some time inspecting the source code to better understand the issue. From what I observed:
-
pppm/tip4p contains the TIP4P-specific charge mapping required for the virtual M-site.
-
pppm/electrode implements the ElectrodeKSpace interface required by the ELECTRODE package.
-
However, I could not find a KSpace style that combines both capabilities.
This made me wonder whether this combination is currently unsupported, or whether I am simply missing the correct way to set it up.
So my questions are:
-
Is TIP4P currently supported together with fix electrode/conp?
-
If not, is this due to a fundamental algorithmic limitation, or is it simply an unimplemented feature?
-
Would a combined implementation (e.g. a TIP4P-aware pppm/electrode) be the intended direction for adding such support?
I would appreciate any clarification from the developers. If this functionality is simply not implemented yet, I would also be interested in contributing to such an implementation.
Thank you very much.