The Poisson-Boltzmann equation (PBE) provides a “fast” and approximate
method for calculating the effects of solvent on electrostatic
interactions in the modeled system. The current solution of the
PBE in CONGEN has one unique feature,
it can spread the charge of each atom over the van der Waals volume
which results in superior convergence properties and
makes the calculation less dependent on the position
of the system with respect to the grid^{1}.
In addition, CONGEN can display the partition of the Poisson-Boltzmann energy
across all the atoms in the system, see the `EPBE` property described
in Atom Properties.

The implementation provides two capabilities. First, one can perform individual electrostatic calculations on any set of atoms within the system. Second, one can replace the Coulomb electrostatic energy with the Poisson-Boltzmann energy in the context of a conformational search, see Poisson-Boltzmann Options. We hope to increase the applicability of this methodology in the future.

[1]
R. E. Bruccoleri,
“Grid Positioning Independence and the Reduction of Self-Energy in the
Solution of
the Poisson-Boltzmann Equation”, *J. Comput. Chem.* **14**, 1417-1422 (1993).