# Module MMTK.Solvation

See also the example MolecularDynamics/solvation.py.

## Functions

- numberOfSolventMolecules()

  Returns the number of solvent molecules of type solvent that must be added to universe, in addition to whatever it contains already, to obtain the specified solvent density.

- addSolvent()

  Scales up the universe by scale_factor and adds as many molecules of type solvent (a molecul object or a string) as are necessary to obtain the specified solvent density, taking account of the solute molecules that are already present in the universe. The molecules are placed at random positions in the scaled-up universe, but without overlaps between any two molecules.

- shrinkUniverse()

  Shrinks universe, which must have been scaled up by Function:MMTK.Solvation.addSolvent, back to its original size. The compression is performed in small steps, in between which some energy minimization and molecular dynamics steps are executed. The molecular dynamics is run at the given temperature, and an optional trajectory (a MMTK.Trajectory.Trajectory object or a string, interpreted as a file name) can be specified in which intermediate configurations are stored.