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. 2014 Aug 28;118(38):11007–11027. doi: 10.1021/jp503372v

Table 10. Relative Solvation Free Energy ΔΔGgas→aq(MM → QM) (in kcal/mol) with Different QM and QM-MM Electrostatic Hamiltoniansa.

    DFTB2 SCC-DFTBPR DFTB3/3OB
solute MM ref. (Exp.)b Coulomb Klopman–Ohno (eq 5)c Coulomb
H2O –6.6 (−6.3) +4.4   +1.7
CH3COOH –4.5 (−6.7) –0.1 –0.0 (+0.0) –3.4
CH3COO –81.9 (−77.6/–80.7163) +3.1 13.1 (15.3) –5.4
CH3O –102.2 (−95.0) +6.8 23.8 (24.9) –3.9
H3PO4 –15.2 (−26.0) –1.4 –3.9 (−3.8) –8.8
H2PO4 –80.8 (−76.0) –1.7 10.1 (11.1) –17.2
a

The MM here is the CHARMM22 force field. The water molecules are treated with TIP3P. Unless specified otherwise, the QM atoms use the standard CHARMM van der Waals parameters.

b

The “MM ref.” values are absolute solvation free energies computed following the standard protocol163,164 with periodic boundary conditions; no correction related to the gas/liquid interface has been included.165167 Values in parentheses are experimental values from ref (168) for the first four solutes and from ref (169) for the phosphate species.

c

The values in parentheses use the CHARMM van der Waals parameters for the QM atoms; those without parentheses use the van der Waals parameters optimized in ref (73).