title: AM1-SM2 and PM3-SM3 parameterized SCF solvation models for free energies in aqueous solution.
abstract: Two new continuum solvation models have been presented recently, and in this paper they are explained and reviewed in detail with further examples. Solvation Model 2 (AM1-SM2) is based on the Austin Model 1 and Solvation Model 3 (PM3-SM3) on the Parameterized Model 3 semiempirical Hamiltonian. In addition to the incorporation of phosphorus parameters, both of these new models address specific deficiencies in the original Solvation Model 1 (AM1-SM1), viz., (1) more accurate account is taken of the hydrophobic effect of hydrocarbons, (2) assignment of heavy-atom surface tensions is based on the presence or absence of bonded hydrogen atoms, and (3) the treatment of specific hydration-shell water molecules is more consistent. The new models offer considerably improved performance compared to AM1-SM1 for neutral molecules and essentially equivalent performance for ions. The solute charges within the Parameterized Model 3 Hamiltonian limit the utility of PM3-SM3 for compounds containing nitrogen and possibly phosphorus. For other systems both AM1-SM2 and PM3-SM3 give realistic results, but AM1-SM2 in general outperforms PM3-SM3. Key features of the models are discussed with respect to alternative approaches.
authors.affiliation: U.S. Army Chemical Research Development and Engineering Center, Physics Division, Aberdeen Proving Ground, MD 21010-5423.
authors.forename: C J
authors.initials: CJ
authors.lastname: Cramer
authors.forename: D G
authors.initials: DG
authors.lastname: Truhlar
mesh_terms: D004563:Electrochemistry; D005069:Evaluation Studies as Topic; D006838:Hydrocarbons / Q000737:chemistry; D008956:Models, Chemical; D012996:Solutions; D013500:Surface Tension; D013816:Thermodynamics; D014867:Water
chemical_list: D006838:Hydrocarbons; D012996:Solutions; D014867:Water