i-TTM Model for Ab Initio-Based Ion-Water Interaction Potentials. 1. Halide-Water Potential Energy Functions

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Molecular Modeling

Background:

• Accurate modeling of ion-water interactions is crucial for understanding chemical and biological processes.
• Existing polarizable force fields may not fully capture the complexities of halide-water systems.

Purpose of the Study:

• To develop novel i-TTM potential energy functions for halide ions (F-, Cl-, Br-, I-) and water molecules.
• To ensure compatibility with the ab initio MB-pol water potential for seamless integration.

Main Methods:

• Derivation of i-TTM potentials from electronic structure data.
• Inclusion of explicit two-body repulsion, electrostatics, and dispersion energy.
• Representation of many-body effects using classical polarization within an extended Thole-type model.

Main Results:

• The i-TTM potentials demonstrate high accuracy when compared against high-level electronic structure calculations (CCSD(T)-F12, DF-MP2, DFT).
• Validation across X(-)(H2O)n clusters (n=1-8) shows good agreement with established methods and common polarizable force fields.
• The potentials successfully reproduce key interaction characteristics for various halide ions.

Conclusions:

• The developed i-TTM potentials offer a reliable and accurate description of halide-water interactions.
• These potentials facilitate direct simulations of vibrational spectra for halide-water systems, from small clusters to condensed phases and interfaces.
• The compatibility with MB-pol enhances their utility for complex aqueous system simulations.