Bonded hard-sphere theory and computer simulation of the equation of state of linear fused–hard-sphere fluids

Abstract

The bonded hard-sphere (BHS) theory is extended to fluids consisting of rigid, linear, homonuclear molecules, each of them formed by n fused hard spheres. The theory shows excellent agreement with the Monte Carlo NpT simulation data which are also reported for reduced bond lengths l*=0.5 and n=2, 3, 4, 6, 8, and 10. The accuracy of the BHS prediction in comparison to simulation is similar to that of generalized Flory-dimer theory and superior to that of thermodynamic perturbation theory.

Poisson’s ratio of orientationally disordered hard dumbbell crystal in three dimensions

“…Comparing formulae (20)- (29) with experimental data, we conclude that they approximate the elastic constants of the dumbbells with an accuracy of about 5%.…”

“…In order to verify the quality of the numerical fits to the simulation data obtained for C Ã ij , analytic formulae (20)- (29) have been substituted to (9)-(13) and the obtained curves have been plotted in Fig. 6.…”

“…Formulae (20)- (29) can be used to visualize the changes of the orientational dependence of Poisson's ratio with anisotropy. In Fig.…”

“…In particular, it was shown [23][24][25][26] that a crude model of a diatomic molecule, the hard homonuclear dumbbell -formed by two fused spheres, each of diameter r, with centers separated by distance d -can form the above-mentioned rotator phase besides the fluid and the fully-ordered crystalline phases. It is worth adding that this non-convex 'molecule' is one of the simplest hard bodies and constitutes a starting point for studies of polymers [27][28][29][30]. Hard dumbbells can be characterized by thir reduced bond length, defined as d * = d/r, which is a measure of dumbbell anisotropy.…”

Poisson's ratio of degenerate crystalline phases of three‐dimensional hard dimers and hard cyclic trimers

“…In those papers extensive MC studies were presented concerning the simplest representative of this class -the hard homonuclear dumbbell -a crude model of a diatomic molecule (and the simplest non-convex body as well) formed by two fused hard spheres, each of diameter , s with centers separated by a distance d. It is worth adding that these systems constitute the starting point for studies of polymers [15][16][17][18]. The influence of a reduced bond length, known also as a dumbbell elongation parameter, * d ds ∫ / on the phase diagram and phase stability was thoroughly investigated.…”