Accurate Intermolecular Potentials with Physically Grounded Electrostatics

Area of Science:

• Computational chemistry
• Molecular modeling
• Physical chemistry

Background:

• Accurate force fields are crucial for molecular simulations.
• Existing force fields often neglect charge penetration energy, a key component of intermolecular potentials.
• Polycyclic aromatic hydrocarbons (PAHs) are important in various fields but challenging to model accurately.

Purpose of the Study:

• To develop a novel strategy for incorporating charge penetration energy into molecular force fields.
• To create a balanced force field for accurate simulations of large molecules, specifically PAHs.
• To refine electrostatic interactions by allowing for atomic charge density adjustments.

Main Methods:

• Directly including charge penetration energy using Spackman's pairwise electrostatic energy summation.
• Parametrizing exchange-repulsion and dispersion terms using symmetry-adapted perturbation theory (SAPT) data.
• Deriving force field parameters for polycyclic aromatic hydrocarbons (PAHs) as a proof-of-concept.

Main Results:

• A new method for including charge penetration energy in force fields was successfully developed.
• Force field parameters for PAHs were derived, enabling accurate modeling of their intermolecular interactions.
• The developed force field demonstrated a reduced extent of error cancellation in simulations.

Conclusions:

• The proposed strategy effectively incorporates charge penetration energy into force fields.
• The new force field parameters enable more accurate molecular simulations of large molecules like PAHs.
• This work provides a more balanced and reliable approach to molecular force field development.