APBS is a software package for the numerical solution of the Poisson-Boltzmann equation, a popular continuum model for describing electrostatic interactions between molecular solutes over a wide range of length scales. <http://www.poissonboltzmann.org/>.
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Really raised the bar!
nice and simple GUI, i like it a lot better.
And, it is free for us to use.
I have used this program for and it is great.