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Bermejo, F. J.; Fåk, B.; Bennington, S. M.; Fernández-Perea, Ricardo; Cabrillo, C.; Dawidowski, J.; Fernández‐Díaz, M. T.; Verkerk, P.

doi:10.1103/physrevb.60.15154

Cited by 57 publications

(36 citation statements)

References 24 publications

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“…The sample was obtained from high-purity hydrogen gas transformed to para-H 2 by forcing it to pass through an activated catalyst, in a similar procedure as described in a previous paper. 7 The sample holder was an aluminum cylinder, 7 mm in diameter and 30 mm high. A vanadium cylinder 10 mm in diameter and 50 mm in height was employed to calibrate the absolute scale.…”

Section: Methodsmentioning

confidence: 99%

Static structure factor of liquid parahydrogen

et al. 2004

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The single-differential neutron-scattering cross section of liquid parahydrogen has been measured at 15.2 K and 2 bars of applied pressure by means of low-energy neutron diffraction. Our experimental conditions enable the direct observation of the peak of the liquid structure factor and therefore largely improve the signal-to-noise ratio with respect to measurements carried out using higher-energy neutron diffraction. This avoids the need of performing corrections of approximate nature to the measured cross section that is dominated by molecular rotational components if measured by conventional neutron diffraction.

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Section: Methodsmentioning

confidence: 99%

Static structure factor of liquid parahydrogen

et al. 2004

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“…Although it is known that liquid para-hydrogen may be treated as a Boltzmann particle near its triple point (23), it still exhibits some of the hallmarks of a highly quantum liquid. In fact, recent neutron scattering experiments of Bermejo et al (24) have uncovered the existence of collective excitations that are absent in the classical fluid. These quantum excitations are a precursor of some of the collective modes that exist in the superfluid state.…”

Section: Application To Self-diffusion Of Liquid Para-hydrogenmentioning

confidence: 99%

The calculation of transport properties in quantum liquids using the maximum entropy numerical analytic continuation method: Application to liquid para -hydrogen

Rabani

Reichman

Krilov

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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We present a method based on augmenting an exact relation between a frequency-dependent diffusion constant and the imaginary time velocity autocorrelation function, combined with the maximum entropy numerical analytic continuation approach to study transport properties in quantum liquids. The method is applied to the case of liquid para-hydrogen at two thermodynamic state points: a liquid near the triple point and a high-temperature liquid. Good agreement for the self-diffusion constant and for the real-time velocity autocorrelation function is obtained in comparison to experimental measurements and other theoretical predictions. Improvement of the methodology and future applications are discussed.O ne of the major goals of, and perhaps the most challenging problem in, computational statistical mechanics is the simulation of quantum dynamics in condensed phases. In principle, the density matrix formalism provides all the tools necessary to study equilibrium and time-dependent properties of any chemical system. In practice, however, the exact solution of the time-dependent quantum Wigner-Liouville equation is possible for a very limited class of simple systems, and the numerical solution for a general many-body system is not possible because of the well known phase cancellation problem (the sign problem).This problem has led to a variety of different techniques to include the effects of quantum fluctuations on the dynamic response of the system. One of the viable alternatives to the exact quantum mechanical solution is the use of techniques that are ''semiclassical'' in nature; namely, the dynamic response is obtained with the aid of classical trajectories (1). Although such techniques appear promising, technical issues have prevented their use in describing dynamics in realistic quantum liquids.Another class of methods that has been used with success in a variety of problems involves sophisticated numerical analytical continuation of exact imaginary-time path-integral Monte Carlo (PIMC) data (2, 3). These methods have been applied to a variety of condensed phase problems, including the dynamics of an excess electron solvated in water (4), helium and xenon (5), vibrational relaxation (6, 7), optical spectroscopy (6-8), adiabatic reaction dynamics (9, 10), dynamics in various quantum lattice models (11,12), and density fluctuations in superfluid helium (13). However, the application of these approaches to study density fluctuations (13) and transport properties (4) in quantum liquids has not been completely successful.In this paper, we show that analytic continuation methods can be used successfully to study the transport properties of a ''realistic'' liquid. We express the imaginary time velocity autocorrelation function, which is obtained from a suitable PIMC method (14), in terms of a frequency-dependent diffusion constant and use the maximum entropy method to analytically continue the imaginary time data to real time and thus obtain the self-diffusion constant and the velocity autocorrelation function. We use ...

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“…The latter is found to be ubiquitous in molten metallic alloys 29 or in pure metals 30 and is known to be crucial to enable the decay of phonon excitations. 31 An estimate of the generalized high-frequency elastic constant C 11 (Q) may be obtained from the relationship 32…”

Section: Discussionmentioning

confidence: 99%

Microscopic structure of Fe-Ni and Fe-Ni-S molten alloys of geophysical interest

et al. 2004

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0.15 . From data at hand no clear evidence of the clustering of sulfur within the Fe-Ni matrix is found. In contrast, the addition of sulfur leads to significant changes in structural and some dynamical properties that can be inferred from knowledge of the static structure factors. Such dynamical changes seem to arise as a result of a strong decrease of the elastic moduli of the alloys resulting from interactions with a light element rather than from a density effect.

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Microscopic collective dynamics in liquidpara−H2

Cited by 57 publications

References 24 publications

Static structure factor of liquid parahydrogen

Static structure factor of liquid parahydrogen

The calculation of transport properties in quantum liquids using the maximum entropy numerical analytic continuation method: Application to liquid para -hydrogen

Microscopic structure of Fe-Ni and Fe-Ni-S molten alloys of geophysical interest

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