Fluids of Lennard-Jones spheres with dipoles and tetrahedral quadrupoles

In this paper we present molecular dynamics (MD) results for fluids of Lennard-Jones particles with permanent dipole and quadrupole moments similar to those of the water molecule. We consider both the true quadrupole tensor of water and the tetrahedral quadrupole approximation which is convenient in theoretical work. The linearized and quadratic hypernettedchain (LHNC and QHNC) integral equation approximations are solved for the tetrahedral quadrupole model and detailed comparisons are made with the MD calculations. It is found that both theories are more accurate at relatively high densities with the QHNC giving better results for most fluid properties.

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