A new insight on the structural changes of linear quadrupole liquids

Abstract

Molecular-dynamics simulations for linear quadrupole liquids are presented. The study is carried out for two different molecular lengths at constant density and a number of temperatures and quadrupole moments. All the simulated thermodynamic states correspond to the condensed phases and some of them show typical features of a solid structure. Furthermore, a change on the preferred intermolecular orientation in the liquid phase is observed from a shifted parallel molecular arrangement to a perpendicular orientation as the quadrupole raises. This change depends on the quadrupole moment as well as on the molecular length and is put in relation with the solid structure of different "diatomic" molecules such as nitrogen, ethane, and acetylene. The appearance of a plastic solid phase at low quadrupole moment and density is also justified. A thoroughly discussion about the availability of classical perturbation theories for this kind of systems is presented.

Influence of the Displacement out of the Center of Mass and Nonaxiality of the Dipole on the Thermodynamics of Liquids Composed of Linear Dipole Molecules

“…The inclusion of dipoles or charges has as practical consequence an increase of computational time for both kinds of potentials, but the same relation keeps for polar molecules. Computation of site−site correlation functions can also be implemented in our algorithm at a negligible computational cost. , In spite of its simplicity, coarse-grained models considering algorithms close to ours have been successfully used in very different fields. – …”