Modified Poisson equations for calculating solvation free energy

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Theoretical Chemistry

Background:

• Dielectric polarization (P) is essential for determining solvation free energy.
• P is a product of electric dipole per solvent (p) and relative solvent molecular density (g).
• Calculating p and g traditionally relies on complex simulations.

Purpose of the Study:

• To develop a modified Poisson equation approach for calculating dielectric polarization (P).
• To estimate boundary conditions for electric field (E) and its gradient (∇xE).
• To explore the dependence of P and g on numerical analysis parameters.

Main Methods:

• Modified Poisson equations were used to calculate E and ∇xE.
• Strategies for estimating boundary conditions were proposed.
• The method was applied to a system of two charged atoms in a water cluster.

Main Results:

• Calculated values for P and g showed good agreement with molecular dynamics simulations.
• The electric potential at solute atoms and solvation free energy matched simulation results.
• The method's dependence on numerical parameters was analyzed.

Conclusions:

• The modified Poisson equation approach provides an accurate and efficient alternative for calculating dielectric polarization and solvation free energy.
• This method offers a viable computational strategy for solvation studies.
• The findings support the theoretical framework linking electric fields, molecular density, and solvation energetics.