[apbs-users] Electric field at active site

[mats]

Dear all,

I am new to APBS and wonder if there is a straightforward way to obtain the electric field vector at a user-defined point (e.g. at the substrate binding site of an enzyme). Are there special keywords for that or do I need to write a script that computes the field vector as the gradient of the electrostatic potential from a number of neighboring grid points? I would like to use the field vector in a subsequent quantum mechanical calculation. I hope this is not a completely trivial question.

Thank you so much in advance,
Mats