Calculation of Hildebrand solubility parameters

Case Study Provider:
X-Ability Co., Ltd.

Overview

The Hildebrand solubility parameter (SP value, δ) is the square root of the heat of evaporation normalised by the specific volume [1]. Substances with similar SP values are more likely to be miscible or soluble in each other. Hildebrand SP parameters are easily obtained through simulations and experiments and utilized in a wide range of fields, from materials development to drug discovery.

In this case study, the Hildebrand solubility parameters of seven organic compounds were calculated with Matlantis and compared with experimental values [2,3] and results from GAFF force field calculations [4].

Sample scripts for this calculation case study are available on matlantis-contrib.
・https://github.com/matlantis-pfcc/matlantis-contrib/tree/main/matlantis_contrib_examples/solubility_parameter

Calculation models and methods

The SP values were calculated according to the formula in Fig.

In this formula, E_vapor and E_liquid are the potential energies per molecule in the vapor and liquid phases, respectively. ρ is the average density calculated by the NPT calculation and M is the molecular weight. <> represents the ensemble average. The computational conditions for the MD calculations are shown in the table. Energy minimisations were performed before the MD calculations.

The calculated systems were modeled using Winmostar [5] .

Calculation Results and Discussion

The figure and table show the results of the Hildebrand solubility parameters for each substance compared to the experimental [2, 3] and calculated [2, 4] values, where R² is the correlation coefficient with the experimental values. In this case study, the SP values obtained using PFP show a better correlation with experimental data compared to those obtained using GAFF.

Calculation Conditions