2016/05/15 by Cortes-Morales, E. C., Elizondo-Aguilera, L. F., Medina-Noyola, M.
#FOS: Physical sciences #Soft Condensed Matter (cond-mat.soft) #Statistical Mechanics (cond-mat.stat-mech)
paper · doi:10.48550/arxiv.1605.04485
The non-equilibrium self-consistent generalized Langevin equation theory of irreversible processes in liquids is extended to describe the positional and orientational thermal fluctuations of the instantaneous local concentration profile n(r,Ω,t) of a suddenly-quenched colloidal liquid of particles interacting through non spherically-symmetric pairwise interactions, whose mean value n(r,Ω,t) is constrained to remain uniform and isotropic, n(r,Ω,t)=n(t). Such self-consistent theory is cast in terms of the time-evolution equation of the covariance σ(t)=δnlm(k;t) δn†lm(k;t) of the fluctuations δnlm(k;t)=nlm(k;t) -nlm(k;t) of the spherical harmonics projections nlm(k;t) of the Fourier transform of n(r,Ω,t). The resulting theory describes the non-equilibrium evolution after a sudden temperature quench of both, the static structure factor projections Slm(k,t) and the two-time correlation function Flm(k,τ;t)≡δnlm(k,t)δnlm(k,t+τ), where τ is the correlation delay time and t is the evolution or waiting time after the quench. As a concrete and illustrative application we use the resulting self-consistent equations to describe the irreversible processes of equilibration or aging of the orientational degrees of freedom of a system of strongly interacting classical dipoles with quenched positional disorder.