Simulation of dynamical properties of normal and superfluid helium.
Akira Nakayama,Nancy Makri +1 more
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This simulation demonstrates that the peak enhancement observed in the neutron scattering experiments below the transition temperature arises exclusively from particle exchange, illuminating the role of Bose-statistical effects on the dynamics of the quantum liquid.Abstract:
The formation of a superfluid when 4He is cooled below the characteristic lambda transition temperature is accompanied by intricate quantum mechanical phenomena, including the emergence of a Bose condensate. A combination of path integral and semiclassical techniques is used to calculate the single-particle velocity autocorrelation function across the normal-to-superfluid transition. We find that the inclusion of particle exchange alters qualitatively the shape of the correlation function below the characteristic transition temperature but has no noticeable effect on the dynamics in the normal phase. The incoherent structure factor extracted from the velocity autocorrelation function is in very good agreement with neutron scattering data, reproducing the width, height, frequency shift, and asymmetry of the curves, as well as the observed increase in peak height characteristic of the superfluid phase. Our simulation demonstrates that the peak enhancement observed in the neutron scattering experiments below the transition temperature arises exclusively from particle exchange, illuminating the role of Bose-statistical effects on the dynamics of the quantum liquid.read more
Citations
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Multiple coherent states for first-principles semiclassical initial value representation molecular dynamics
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Linearized semiclassical initial value time correlation functions using the thermal Gaussian approximation: applications to condensed phase systems.
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References
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Journal ArticleDOI
Nonequilibrium Self-Assembly of Long Chains of Polar Molecules in Superfluid Helium
K. Nauta,R. E. Miller +1 more
TL;DR: It is shown that in the low-temperature environment of superfluid helium droplets, long-range dipole-dipole forces acting between two polar molecules can result in the self-assembly of noncovalently bonded linear chains, suggesting a design strategy for the growth of new nanoscale oligomers composed of monomers with defined dipole (or higher order) moment directions.
Journal ArticleDOI
Efficient and general algorithms for path integral Car–Parrinello molecular dynamics
TL;DR: In this paper, an efficient Car–Parrinello path integral molecular dynamics algorithm, sufficiently general to include the use of ultrasoft pseudopotentials is introduced and difficulties encountered when combining thermostats and transformations of the Cartesian ‘‘bead’’ coordinates with the generalized orthonormality condition are circumvented.
Journal ArticleDOI
Ab Initio Calculations for Helium: A Standard for Transport Property Measurements
TL;DR: It is pointed out that, in the case of helium, calculations of virial coefficients and transport properties based on an accurate state-of-theart ab initio potential are now sufficiently accurate that the traditional practices can be usefully reversed.
Journal ArticleDOI
Theory of Slow Neutron Scattering by Liquids. I
TL;DR: In this paper, a general discussion of scattering in liquids has been given, based on Van Hove's formalism, and the scattering cross section has been expressed in terms of velocity correlation functions.
Book
Excitations in liquid and solid helium
Henry R. Glyde,Robert Hallock +1 more
TL;DR: In this paper, the authors present a model of S(Q,omega) in liquid 3He and the impulse approximation to the dynamic susceptibility of liquid 4He...
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