The phase diagram of carbon dioxide from correlation functions and a many-body potential

The phase stability and equilibria of carbon dioxide is investigated from 125 -- 325K 1 10,000 atm using extensive molecular dynamics (MD) simulations the Two-Phase Thermodynamics (2PT) method. We devise a direct approach for calculating diagrams in general, by considering separate chemical potentials isolated at specific points on P-T diagram. unique ability 2PT to accurately efficiently approximate entropy Gibbs energy liquids thus allows assignment boundaries relatively short ($\mathrm{\sim}$ 100ps) MD simulations. validate our critical properties flexible Elementary Physical Model 2 (FEPM2), showing good agreement with previous results. show, however, that incorrect description short-range Pauli force lack charge polarization leads deviations experiments high pressures. develop many-body, fluctuating model CO${}_{2}$, termed CO${}_{2}$-Fq, level quantum mechanics (QM) calculations, captures condensed vibrational solid (including Fermi resonance 1378 cm${}^{-1}$) as well diffusional liquid, leading overall excellent over entire This work provides an efficient computational determining arbitrary systems underscore role QM reorganization physics stability.