An accurate density response function χ(q) of superfluid 4He at zero temperature and at freezing pressure, up to about q=8 Å−1, has been obtained via dynamic structure factors, S(q,ω), extracted from imaginary time density–density correlation functions computed with an exact Path Integral projector method. A new statistical approach (Vitali et al. in Phys. Rev. B 82:174510, 2010) to inverse problems has been used to extract S(q,ω); contrarily to analogous “analytic continuation” approaches, this new method has been found able to separate a well defined elementary excitation peak from multi–phonon contributions. We have applied density functional theory (DFT) to a superfluid–solid transition with the obtained χ(q). With this accurate input, DFT gives unphysically unstable superfluid against solidification which is consistent with conventional works. We discuss the possible defect of DFT.

Accurate density response function of superfluid 4He at freezing pressure : is DFT successful for superfluid freezing? / T. Minoguchi, D. E. Galli. - In: JOURNAL OF LOW TEMPERATURE PHYSICS. - ISSN 0022-2291. - 162:3/4(2011), pp. 160-166.

Accurate density response function of superfluid 4He at freezing pressure : is DFT successful for superfluid freezing?

D. E. Galli
Ultimo
2011

Abstract

An accurate density response function χ(q) of superfluid 4He at zero temperature and at freezing pressure, up to about q=8 Å−1, has been obtained via dynamic structure factors, S(q,ω), extracted from imaginary time density–density correlation functions computed with an exact Path Integral projector method. A new statistical approach (Vitali et al. in Phys. Rev. B 82:174510, 2010) to inverse problems has been used to extract S(q,ω); contrarily to analogous “analytic continuation” approaches, this new method has been found able to separate a well defined elementary excitation peak from multi–phonon contributions. We have applied density functional theory (DFT) to a superfluid–solid transition with the obtained χ(q). With this accurate input, DFT gives unphysically unstable superfluid against solidification which is consistent with conventional works. We discuss the possible defect of DFT.
4He; Analytic continuation; Density functional theory; Density response function; DFT; Quantum freezing; Solidification; Superfluid
Settore FIS/03 - Fisica della Materia
2011
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/149936
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