Molecular Dynamics Simulation of Density of Supercritical Carbon Dioxide

Supercritical carbon dioxide (scCO2) is well-known because of its tunable solvent power. In addition, its transport properties are larger than normal liquids which are favorable in the chemical industries. These unique properties make scCO2 attractive as reaction and/or extraction media. Consequently, these desirable potentials motivate researchers to investigate details of scCO2 systematically. This study aims to use the powerful tool of molecular dynamics simulation to investigate scCO2 from two different points of view. In the first approach, scCO2 was simulated as a rigid molecule, while in the second approach -which has more popularity- scCO2 molecules were considered to be flexible, with dynamic bonds and angles. Simulations were carried out in wide ranges of temperature (310 to 500 K) and pressure (7 to 35 MPa). Results show that the non-rigid model reproduces experimental density data with appreciably high deviation, even more than 100%, while the rigid rotor model reproduces the data with high accuracy. This considerable difference between simulation results and experimental shows that modeling CO2 molecules in molecular dynamics simulations as a rigid rotor is the better alternative

Keywords:

Molecular Dynamics Simulation , Supercritical Carbon Dioxide , Density , Rigid-Rotor Harmonic-Oscillator , Physical Property Prediction