title: Many-body effects are essential in a physically motivated CO2 force field.
abstract: We develop a physically motivated many-body force field for CO(2), incorporating explicit three-body interactions parameterized on the basis of two- and three-body symmetry adapted perturbation theory (SAPT) calculations. The potential is parameterized consistently with, and builds upon, our successful SAPT-based two-body CO(2) model ("Schmidt, Yu, and McDaniel" (SYM) model) [K. Yu, J. G. McDaniel, and J. R. Schmidt, J. Phys Chem B 115, 10054 (2011)]. We demonstrate that three-body interactions are essential to achieve an accurate description of bulk properties, and that previous two-body models have therefore necessarily exploited large error cancellations to achieve satisfactory results. The resulting three-body model exhibits excellent second/third virial coefficients and bulk properties over the phase diagram, yielding a nearly empirical parameter-free model. We show that this explicit three-body model can be converted into a computationally efficient, density/temperature-dependent two-body model that reduces almost exactly to our prior SYM model in the high-density limit.
authors.affiliation: Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Kuang
authors.initials: K
authors.lastname: Yu
authors.forename: J R
authors.initials: JR
authors.lastname: Schmidt
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D011789:Quantum Theory; D013696:Temperature
chemical_list: D002245:Carbon Dioxide