. Author manuscript; available in PMC: 2013 Nov 13.

Published in final edited form as: J Chem Theory Comput. 2012 Sep 12;8(11):4405–4412. doi: 10.1021/ct300613v

Table 6.

Comparison of Solvation free energies (in kcal/mol) from experiment, quantum mechanical calculations, and MD simulations reported here. All values are in kcal/mol. For the quantum mechanical calculations, Gaussian03 values using B3LYP, a aug-cc-pVTZ basis set and PCM solvation model are reported. The TI results differ from the target values in 3 and 4 because they include the polarization correction term to be comparable to experiment and QM results.

Phosphate	Experiment	QM	TI
$P O_{4}^{3 -}$	-660.9⁴¹/-637³⁹	-495.3	-632.3
$H P O_{4}^{2 -}$	-299³⁹	-232.9	-263.7
$H_{2} P O_{4}^{-}$	-111.1⁴¹/-68⁴⁰/-76³⁹	-71.5	-75.3
H ₃ PO ₄	-26³⁹	-22.3	-8.3