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.
|Titolo:||Accurate density response function of superfluid 4He at freezing pressure : is DFT successful for superfluid freezing?|
GALLI, DAVIDE EMILIO (Ultimo)
|Parole Chiave:||4He; Analytic continuation; Density functional theory; Density response function; DFT; Quantum freezing; Solidification; Superfluid|
|Settore Scientifico Disciplinare:||Settore FIS/03 - Fisica della Materia|
|Data di pubblicazione:||2011|
|Digital Object Identifier (DOI):||10.1007/s10909-010-0311-3|
|Appare nelle tipologie:||01 - Articolo su periodico|