Department of Chemistry, University of Gothenburg, Gothenburg 41296, Sweden.
J Chem Phys. 2011 Jan 21;134(3):034312. doi: 10.1063/1.3519022.
A number of simple pair interaction potentials of the carbon dioxide molecule are investigated and found to underestimate the magnitude of the second virial coefficient in the temperature interval 220-448 K by up to 20%. Also the third virial coefficient is underestimated by these models. A rigid, polarizable, three-site interaction potential reproduces the experimental second and third virial coefficients to within a few percent. It is based on the modified Buckingham exp-6 potential, an anisotropic Axilrod-Teller correction, and Gaussian charge densities on the atomic sites with an inducible dipole at the center of mass. The electric quadrupole moment, polarizability, and bond distances are set to equal experiment. Density of the fluid at 200 and 800 bars pressure is reproduced to within some percent of observation over the temperature range 250-310 K. The dimer structure is in passable agreement with electronically resolved quantum-mechanical calculations in the literature, as are those of the monohydrated monomer and dimer complexes using the Gaussian charge polarizable model water potential. Qualitative agreement with experiment is also obtained, when quantum corrections are included, for the relative stability of the trimer conformations, which is not the case for the pair potentials.
研究了二氧化碳分子的一些简单对相互作用势能，发现这些模型在 220-448 K 的温度范围内将第二维里系数的大小低估了多达 20%。这些模型还低估了第三维里系数。刚性、极化、三位点相互作用势能可以将实验的第二和第三维里系数精确到几个百分点以内。它基于改进的 Buckingham exp-6 势能、各向异性的 Axilrod-Teller 修正和原子位点上的高斯电荷密度，质心处有诱导偶极子。电四极矩、极化率和键长与实验相等。在 250-310 K 的温度范围内，在 200 和 800 巴压力下的流体密度与观测值相差几个百分点以内。二聚体结构与文献中电子分辨量子力学计算基本一致，使用高斯电荷极化模型水势能的单水合单体和二聚体复合物也是如此。当包括量子修正时，对于三聚体构象的相对稳定性也得到了定性的一致，而对于对相互作用势能则不然。
