A Fully Flexible Potential Model for Carbon Dioxide

• Published in: Chinese journal of chemical engineering Vol. 17; no. 2; pp. 268 - 272
• Main Author: 朱爱梅 张新波 刘庆林 张秋根
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2009
• Subjects: carbon dioxide; fully flexible potential model; molecular simulations; radial distributions; 势模型; 实验数据; 平均绝对偏差; 蒙特卡罗技术; 超临界二氧化碳; 超临界条件; 超临界状态; 非线性分子; fully flexible potential model; carbon dioxide; molecular simulations; radial distributions
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/S1004-9541(08)60204-9

A fully flexible potential model for carbon dioxide has been developed to predict the vapor-liquid coexistence properties using the NVT-Gibbs ensemble Monte Carlo technique （GEMC）. The average absolute deviation between our simulation and the literature experimental data for saturated liquid and vapor densities is 0.3% and 2.0%, respectively. Compared with the experimental data, our calculated results of critical properties （7.39 MPa, 304.04 K, and 0.4679 g·cm^-3） are acceptable and are better than those from the rescaling the potential parameters of elementary physical model （EPM2）. The agreement of our simulated densities of supercritical carbon dioxide with the experimental data is acceptable in a wide range of pressure and temperature. The radial distribution function estimated at the supercritical conditions suggests that the carbon dioxide is a nonlinear molecule with the C=O bond length of 0.117 nm and the O=C=O bond angle of 176.4°, which are consistent with Car-Parrinello molecular- dynamics （CPMD）, whereas the EPM2 model shows large deviation at supercritical state. The predicted self-diffusion coefficients are in agreement with the experiments.