Non-equilibrium relaxation and aging in the dynamics of a dipolar fluid quenched towards the glass transition

The recently developed non-equilibrium self-consistent generalized Langevin equation theory of the dynamics of liquids of non-spherically interacting particles [J. Phys. Chem. B 120, 7975 (2016)] is applied to the description of the irreversible relaxation of a thermally and mechanically quenched dipolar fluid. Specifically, we consider a dipolar hard-sphere liquid quenched (at tw = 0) from full equilibrium conditions towards different ergodic–non-ergodic transitions. Qualitatively different scenarios are predicted by the theory for the time evolution of the system after the quench (tw > 0), that depend on both the kind of transition approached and the specific features of the protocol of preparation. Each of these scenarios is characterized by the kinetics displayed by a set of structural correlations, and also by the development of two characteristic times describing the relaxation of the translational and rotational dynamics, allowing us to highlight the crossover from equilibration to aging in the system and leading to the prediction of different underlying mechanisms and relaxation laws for the dynamics at each of the glass transitions explored.

Radial Distribution Function for a Hard Sphere Liquid: A Modified Percus-Yevick and Hypernetted-Chain Closure Relations

Establishment of the radial distribution function by solving the Ornstein-Zernike equation is still an important problem, even more than a hundred years after the original paper publication. New strategies and approximations are common in the literature. A crucial step in this process consists in defining a closure relation which retrieves correlation functions in agreement with experiments or molecular simulations. In this paper, the functional Taylor expansion, as proposed by J. K. Percus, is applied to introduce two new closure relations: one that modifies the Percus‑Yevick closure relation and another one modifying the Hypernetted-Chain approximation. These new approximations will be applied to a hard sphere system. An improvement for the radial distribution function is observed in both cases. For some densities a greater accuracy, by a factor of five times compared to the original approximations, was obtained.

Study of Energy of Formation for FexNi1-x Liquid Binary Alloys

In this present study we have systematically calculated the free energy of formation for FexNi1-x binary alloys at a thermodynamic state T = 1920 K. A microscopic theory bases on first order perturbation theory along with a reference hard sphere liquid has been applied. The interionic interaction is described by Bretonnet-Silbert local pseudopotential that capable of takes into account the s-d hybridization in electro-ion interaction in transition metals. The effective hard sphere diameters have been determined using linearized Weeks-Chandler-Andersen (LWCA) perturbation theory and the partial structure calculated in line with Ashcroft and Langreths original work. The calculated theoretical value and available experimental data for free energy of formation are in agreement quite satisfactorily.