STRUCTURAL AND THERMODYNAMIC PROPERTIES OF FLUID CARBON-DIOXIDE FROM A NEW AB-INITIO POTENTIAL-ENERGY SURFACE

An intermolecular potential energy surface for the carbon dioxide dime r is calculated fully ab initio using a large basis set and including electron correlation. From this potential the dimer structure and the second virial coefficients are determined. In addition, it is applied in molecular dynamics simulations to obtain the fluid structure, the p ressure, the internal energy, the thermal pressure coefficient, and th e molar heat at constant volume. The results are compared with those f rom simulations with a previous ab initio potential. In this way we ga in information regarding the sensitivity of each property to the quali ty of the quantum chemically obtained potential. Equilibration of carb on dioxide simulations must be done with great care due to the very sl ow energy transfer between the intramolecular vibrations and the other degrees of freedom. This point is addressed in same detail. (C) 1998 American Institute of Physics. [S0021-9606(98)50532-6]