FEHALO — Specify the fraction of non-hydrogenic solvent atoms that are electronegative halogen atoms.
FEHALO=n.nn
The FEHALO=n.nn keyword specifies the fraction of non-hydrogenic solvent atoms that are electronegative halogen atoms (fluorine, chlorine, and bromine). Hence, the value must necessarily be between zero and one for all solvents. The file solvent.data contains values of FEHALO for many common organic solvents, but FEHALO can be calculated simply for any organic solvent.