Comparison of Implicit and Explicit Solvent Models
for the Calculation of Solvation Free Energy in Organic Solvents
Jin Zhang
Haiyang Zhang
Tao Wu
Qi Wang
David van der Spoel
10.1021/acs.jctc.7b00169.s001
https://acs.figshare.com/articles/journal_contribution/Comparison_of_Implicit_and_Explicit_Solvent_Models_for_the_Calculation_of_Solvation_Free_Energy_in_Organic_Solvents/4725598
Quantitative prediction of physical
properties of liquids is important
for many applications. Computational methods based on either explicit
or implicit solvent models can be used to approximate thermodynamics
properties of liquids. Here, we evaluate the predictive power of implicit
solvent models for solvation free energy of organic molecules in organic
solvents. We compared the results calculated with four generalized
Born (GB) models (GB<sup>Still</sup>, GB<sup>HCT</sup>, GB<sup>OBC</sup>I, and GB<sup>OBC</sup>II), the Poisson–Boltzmann (PB) model,
and the density-based solvent model SMD with previous solvation free
energy calculations (Zhang et al. <i>J. Chem. Inf. Model.</i> <b>2015</b>, <i>55</i>, 1192–1201) and experimental
data. The comparison indicates that both PB and GB give poor agreement
with explicit solvent calculations and even worse agreement with experiments
(root-mean-square deviation ≈ 15 kJ/mol). The main problem
seems to be the prediction of the apolar contribution, which should
include the solvent entropy. The quantum mechanical-based SMD model
gives significantly better agreement with experimental data than do
PB or GB, but it is not as good as explicit solvent calculation results.
The dielectric constant ε of the solvent is found to be a powerful
predictor for the polar contribution to the free energy in implicit
models; however, the Onsager relation may not hold for realistic solvent,
as suggested by explicit solvent and SMD calculations. From the comparison,
we also find that with an optimization of the apolar contribution,
the PB model gives slightly better agreement with experiments than
the SMD model, whereas the correlation between the optimized GB models
and experiments remains poor. Further optimization of the apolar contribution
is needed for GB models to be able to treat solvents other than water.
2017-02-28 00:00:00
apolar contribution
Organic Solvents Quantitative prediction
PB
optimized GB models
HCT
Explicit Solvent Models
OBC
calculation
Solvation Free Energy
quantum mechanical-based SMD model
II