Ion density fluctuations in liquid metals: the strongly interacting ion-electron plasma

An unified description of liquid metals dynamics based on an interacting two-component model for the ionelectron plasma is tempted. The propagation velocity of the collective modes in alkali and polyvalent metals, derived from inelastic neutron and x-rays scattering experiments, is compared with the estimates obtained by different theoretical approximations for the strongly-interacting plasma. Using accurate results for the electron gas correlation energy, and taking into account the ion finite size effects, a good overall description of a large set of liquid metals is obtained. The observed trend for the damping of the collective modes in liquid metals is also discussed within the framework of the two-component description.Робиться спроба узагальненого опису динамiки рiдких металiв на основi взаємодiючої двокомпонентної моделi для iон-електронної плазми. Швидкiсть поширення колективних мод у лужних та полiвалентних металах, отримана з експериментiв по непружному розсiянню нейтронiв та рентгенiвських променiв, порiвнюється з оцiнками, отриманими рiзними теоретичними наближеннями для сильно взаємодiючої плазми. Використовуючи точнi результати для кореляцiйної енергiї електронного газу та враховуючи ефекти скiнченого розмiру iонiв, отримано в цiлому добрий опис великого набору рiдких металiв. Спостережувана тенденцiя до згасання колективних мод у рiдких металах також обговорюється в рамках двокомпонентного опису

Concerted Proton Tunneling in ordinary ice

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The making of salty ice

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Multi-Scale Study of the Static Structure of Liquid Li

A multi-scale approach is applied to study the static structure of Li70-Bi30 liquid alloy. In order to describe the interatomic interactions in this non-simple metal, we make a set of three empirical pair potentials fit ab-initio computations of the forces and energy in this system. Large scale classical simulations are performed using these fitted potentials from which the partial and total structures are computed. These results are validated by comparison with new experimental neutron data. The partial structure clearly indicates heterocoordination, which is consistent with a marked ionic nature of the bonding, in agreement with earlier electrical resistivity measurements

Multi-Scale Study of the Static Structure of Liquid Li70-Bi30 Alloy

A multi-scale approach is applied to study the static structure of Li70-Bi30 liquid alloy. In order to describe the interatomic interactions in this non-simple metal, we make a set of three empirical pair potentials fit ab-initio computations of the forces and energy in this system. Large scale classical simulations are performed using these fitted potentials from which the partial and total structures are computed. These results are validated by comparison with new experimental neutron data. The partial structure clearly indicates heterocoordination, which is consistent with a marked ionic nature of the bonding, in agreement with earlier electrical resistivity measurements

Quantum Dynamics of H2 and D2 Confined in Hydrate Structures as a Function of Pressure and Temperature

We present an extensive study of the quantum dynamics of molecular hydrogen trapped within the nanocavities of two hydrate structures at low temperatures, namely, clathrate structure II and filled ice structure C1. By inelastic neutron scattering measurements, we investigate a i simple H2 hydrate in clathrate structure II at ambient and high pressure and different temperatures, ii binary He H2 hydrate in clathrate structure II at high pressure and different temperatures, iii simple D2 hydrate in clathrate structure II at ambient pressure and different temperatures, and iv simple H2 hydrate in structure C1 at high pressure and different temperatures. Molecular quantum rotations and translations, as well as combinations of these are identified in the spectra for hydrogen molecules in the small and large cages of clathrate structure II and in the channels of structure C1 and their energy is provide

Cage diffusion in liquid mercury

We present inelastic neutron scattering measurements on liquid mercury at room temperature for wave numbers $q$ in the range 0.3 $< q <$ 7.0 \AA$^{-1}$. We find that the energy halfwidth of the incoherent part of the dynamic structure factor $S(q,E)$ is determinded by a self-diffusion process. The halfwidth of the coherent part of $S(q, E)$ shows the characteristic behavior expected for a cage diffusion process. We also show that the response function at small wave numbers exhibits a quasi-elastic mode with a time scale characteristic of cage diffusion, however, its intensity is larger by an order of magnitude than what would be expected for cage diffusion. We speculate on a scenario in which the intensity of the cage diffusion mode at small wave numbers is amplified through a valence fluctuation mechanism.Comment: 15 pages +5 figure