  We report a development of a new fast surface-based method for numerical
calculations of solvation energy of biomolecules with a large number of charged
groups. The procedure scales linearly with the system size both in time and
memory requirements, is only a few percent wrong for any molecular
configurations of arbitrary sizes, gives explicit value for the reaction field
potential at any point, provides both the solvation energy and its derivatives
suitable for Molecular Dynamics simulations. The method works well both for
large and small molecules and thus gives stable energy differences for
quantities such as solvation energies of molecular complex formation.
