Generalized collective modes for the Lennard-Jones fluid

Longitudinal Dynamics in a Lennard-Jones Binary Liquid: Crossover From Hydrodynamics to the Molecular Regime

“…One should note, that for k > 0.5Å −1 both branches have nearly the same damping coefficients, while in the small wavenumbers limit the branch shown by open boxes tends to a finite nonzero damping coefficient. This is a specific feature of kinetic-like collective modes [11,12]. The branch shown by filled boxes displays almost linear k dependence for imaginary part of the eigenvalue with the slope c = 808 m/s, while its real part for k < 0.3Å −1 behaves almost proportional to a k 2 which is typical of sound excitations.…”

“…In such a way one can systematically target further the effect of concentration or mass ratio onto the dispersion laws for propagating excitations. Recently, the main dynamic processes in the transverse dynamics of a binary equimolar KrAr liquid [8,9] were studied by combining the molecular dynamics (MD) simulations and an analytical generalized collective modes (GCM) approach [10][11][12]. A clear picture of transverse dynamics in terms of two branches of propagating excitations was established: in short-wavelength region the branches show a well observed partial character, describing the dynamics of light and heavy components, while in the long-wavelength region the low-frequency branch exhibits the collective shear-wave dispersion with a propagation gap in k → 0 limit and the high-frequency branch corresponds to the pair of collective optic-like excitations.…”

Wavevector- and frequency-dependent shear viscosity of water: the modified collective mode approach and molecular dynamics calculations

“…Recently [19], a modified formulation of the generalized collective mode (GCM) approach [23][24][25] has been proposed to describe the processes of dynamical polarization in interaction site models of molecular liquids. The modified formulation consistently takes into account non-Markovian terms in the kinetic memory kernels by involving additional dynamical quasivariables leading to the correlation times of higher orders.…”

Propagating Collective Excitations in Molten Salts

“…The imaginary parts of four eigenvalues, which was obtained for the generalized hydrodynamic matrix T(k), constructed on the basis set (13), is shown in figure 2. For all the wavenumbers sampled in this study, we obtained two complex-conjugated pairs of eigenvalues which correspond to the propagating collective excitations.…”

“…Within the generalized collective mode (GCM) approach, proposed originally in reference [6] and developed then in references [12][13][14][15], the collective excitations in the fluids are directly connected with eigenvalues of the so-called generalized hydrodynamic matrix, which determines the time evolution of the system. Such a definition of collective modes is in agreement with the generally accepted principle of statistical physics, when the collective modes are identified with the poles of the relevant Green function or generalized susceptibility.…”