GROMACS version: 5.1.4
GROMACS modification: No
Here post your question
I am using gmx potential to extract the potential profile, charge density profile, electric field profile from gromacs.
The results are larger than I expected.
For example, the following case is a KCl solution between two charged walls with 0.13 C/m^2.
I wonder if the unit of field.xvg is V/nm as it states in the field.
It is with applied voltage?
Yes. electric field 0.25 V/nm is applied in the y direction.
The electric field profile shown in the post is extracted by “gmx potential -d Z”.
Charged Silicon walls are on z = 5 and z = 8.5 nm with 0.13 C/m^2.
I found the reason, so leave the answer here.
The electric field output from the “gmx potential” didn’t consider the dielectric constant, which mean the dielectric constant is equal to 1.
If we are using the SPC/E or other water models and want to know the potential or electric field from the “gmx potential”, the output value is required to be divided by dielectric constant of the water models.
BTW, if we want to output the curve similar to Poisson-Boltzmann equation, choosing the “non-water” to exclude the influence of water can achieve it.
