958 research outputs found
Implementation of the Linear Method for the optimization of Jastrow-Feenberg and Backflow Correlations
We present a fully detailed and highly performing implementation of the
Linear Method [J. Toulouse and C. J. Umrigar (2007)] to optimize
Jastrow-Feenberg and Backflow Correlations in many-body wave-functions, which
are widely used in condensed matter physics. We show that it is possible to
implement such optimization scheme performing analytical derivatives of the
wave-function with respect to the variational parameters achieving the best
possible complexity O(N^3) in the number of particles N.Comment: submitted to the Comp. Phys. Com
High Curie temperature Mn 5 Ge 3 thin films produced by non-diffusive reaction
Polycrystalline Mn 5 Ge 3 thin films were produced on SiO 2 using magnetron
sputtering and reactive diffusion (RD) or non-diffusive reaction (NDR). In situ
X-ray diffraction and atomic force microscopy were used to determine the layer
structures, and magnetic force microscopy, superconducting quantum interference
device and ferromagnetic resonance were used to determine their magnetic
properties. RD-mediated layers exhibit similar magnetic properties as MBE-grown
monocrystalline Mn 5 Ge 3 thin films, while NDR-mediated layers show magnetic
properties similar to monocrystalline C-doped Mn 5 Ge 3 C x thin films with
NDR appears as a CMOS-compatible efficient method to
produce good magnetic quality high-curie temperature Mn 5 Ge 3 thin films
Dynamical structure factor of one-dimensional hard rods
The zero-temperature dynamical structure factor S(q,omega) of one-dimensional hard rods is computed using state-of-the-art quantum Monte Carlo and analytic continuation techniques, complemented by a Bethe ansatz analysis. As the density increases, S(q,omega) reveals a crossover from the Tonks-Girardeau gas to a quasisolid regime, along which the low-energy properties are found in agreement with the nonlinear Luttinger liquid theory. Our quantitative estimate of S(q,omega) extends beyond the low-energy limit and confirms a theoretical prediction regarding the behavior of S(q,omega) at specific wave vectors Q(n) = n2 pi/a, where a is the core radius, resulting from the interplay of the particle-hole boundaries of suitably rescaled ideal Fermi gases. We observe significant similarities between hard rods and one-dimensional He-4 at high density, suggesting that the hard-rods model may provide an accurate description of dense one-dimensional liquids of quantum particles interacting through a strongly repulsive, finite-range potential
One-Dimensional Liquid He-4: Dynamical Properties beyond Luttinger-Liquid Theory
We compute the zero-temperature dynamical structure factor of one-dimensional liquid He-4 by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model
Static density response of one-dimensional soft bosons across the clustering transition
One-dimensional bosons interacting via a soft-shoulder potential are
investigated at zero temperature. The flatness of the potential at short
distances introduces a typical length, such that, at relatively high densities
and sufficiently strong interactions, clusters are formed, even in the presence
of a completely repulsive potential. We evaluate the static density response
function of this system across the transition from the liquid to the cluster
liquid phases. Such quantity reveals the density modulations induced by a weak
periodic external potential, and is maximal at the clustering wavevector. It is
known that this response function is proportional to the static structure
factor in the classical regime at high temperature, while for this
zero-temperature quantum systems, we extract it from the dynamical structure
factor evaluated with quantum Monte Carlo methods.Comment: 7 pages, 3 figures. Proceedings of the "Recent Progress in Many-Body
Theories" international conference, Pohang, South Korea, 201
- …