[gmx-users] how to calculate ESP at certain position

[Zhenyu Meng]

Dear all,
I want to calculate electrostatic potential at a certain position in a box.
I check the available tools and found only g_potential is related with this.
However g_potential give the graph of potential vs. box length(may be z
axis).
So my first question: Is this potential value the potential at the COM of
the group I select?
Second question: how can I calculate the potential at certain position vs.
time?

-- 
Sincerely,
Mr. Meng Zhenyu
Division of Chemistry and Biological Chemistry
School of Physical and Mathematical Sciences
Nanyang Technological University