Generalized Born Implicit Solvent

`Generalized Born implicit solvent (GBIS) is a fast but approximate method for calculating molecular electrostatics in solvent as described by the Poisson Boltzmann equation which models water as a dielectric continuum.
GBIS enables the simulation of atomic structures without including explicit solvent water.
The elimination of explicit solvent greatly accelerates simulations;
this speedup is lessed by the increased computational complexity of the implicit solvent electrostatic calculation and a longer interaction cutoff.
These are discussed in greater detail below.
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http://www.ks.uiuc.edu/Research/namd/