On the non-Gaussian corrections in the self dynamics of semi-quantum fluids

Autor(en)

D. Colognesi, U. Bafile, M. Celli, M. Neumann

Abstrakt

This paper is devoted to the study of the limits of the well-known Gaussian approximation in the self dynamics of quantum systems. After introducing the basic formalism and shortly reviewing the methods used in classical systems to apply corrections to the Gaussian approximation, an extension to quantum fluids is devised, with a particular interest in the so-called semi-quantum fluids, i.e. those in which the single particle momentum distribution approximately retains its Maxwellian form (but not its classical width). In this case a detailed correction scheme for both the short- and the long-time behaviors of the intermediate scattering function is proposed. Subsequently, a practical test of this approach is performed on a high resolution neutron scattering spectrum derived from liquid parahydrogen at T = 14.1 K. Extracting the spectral deviations from the Gaussian approximation with the help of an accurate centroid molecular dynamics simulation, we are able to describe them precisely and to derive the first two correction coefficients in this system by means of a simple fitting procedure. These experimental findings confirm the validity of our approach and show that a description of the self dynamics beyond the Gaussian approximation is necessary even in simple liquids affected by mild quantum effects.

Organisation(en)

Computergestützte Physik und Physik der Weichen Materie

Externe Organisation(en)

Università degli Studi di Roma "Tor Vergata"

Journal

Chemical Physics

Band

446

Seiten

57-64

Anzahl der Seiten

8

ISSN

0301-0104

DOI

https://doi.org/10.1016/j.chemphys.2014.11.007

Publikationsdatum

01-2015

Peer-reviewed

Ja

ÖFOS 2012

103015 Kondensierte Materie, 103006 Chemische Physik, 103019 Mathematische Physik, 103008 Experimentalphysik

Schlagwörter

ASJC Scopus Sachgebiete

Allgemeine Physik und Astronomie, Physical and Theoretical Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/683ecf2e-e8cf-451c-a58b-8ef2327556d0