Many-body effects are essential in a physically motivated CO2 force field

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Materials Science

Background:

• Previous two-body models for carbon dioxide (CO2) force fields relied on error cancellations for accuracy.
• Accurate simulation of CO2 bulk properties requires accounting for many-body interactions.

Purpose of the Study:

• To develop a physically motivated many-body force field for CO2.
• To incorporate explicit three-body interactions for improved accuracy.
• To create a model that accurately predicts CO2 bulk properties.

Main Methods:

• Parameterization of a three-body force field using two- and three-body symmetry adapted perturbation theory (SAPT) calculations.
• Building upon a previously successful SAPT-based two-body CO2 model (SYM model).

Main Results:

• Demonstrated the essential role of three-body interactions for accurate CO2 bulk properties.
• Achieved excellent second/third virial coefficients and phase diagram properties.
• Developed a nearly empirical parameter-free model.

Conclusions:

• The developed three-body CO2 force field provides a significant improvement over previous models.
• The model can be converted into an efficient, density/temperature-dependent two-body model.
• This work offers a more accurate and reliable computational tool for CO2 simulations.