2,985 research outputs found
Quantum Monte Carlo Algorithm Based on Two-Body Density Functional Theory for Fermionic Many-Body Systems: Application to 3He
We construct a quantum Monte Carlo algorithm for interacting fermions using
the two-body density as the fundamental quantity. The central idea is mapping
the interacting fermionic system onto an auxiliary system of interacting
bosons. The correction term is approximated using correlated wave functions for
the interacting system, resulting in an effective potential that represents the
nodal surface. We calculate the properties of 3He and find good agreement with
experiment and with other theoretical work. In particular, our results for the
total energy agree well with other calculations where the same approximations
were implemented but the standard quantum Monte Carlo algorithm was usedComment: 4 pages, 3 figures, 1 tabl
Thermodynamic consistency of energy and virial routes: An exact proof within the linearized Debye-H\"uckel theory
The linearized Debye-H\"uckel theory for liquid state is shown to provide
thermodynamically consistent virial and energy routes for any potential and for
any dimensionality. The importance of this result for bounded potentials is
discussed.Comment: 4 pages, 1 figure; v2: minor change
'We all miss you': Enrico Berlinguer in post-Berlin Wall Italy
Enrico Berlinguer, the former leader of the PCI (Partito comunista italiano - Italian Communist Party), who died in 1984, became the object of popular nostalgia in post-Berlin wall Italy. The paper accounts for the political, historiographical, and even psychological factors behind this nostalgia. The article also highlights how journalists and politicians, both right and left, have used (and abused) Berlinguer’s thought and ideas, making him either a symbol of the morality that is today lacking in Italian politics (the right-wing perspective), or a prophet of the struggle against a broken financial system (the left-wing perspective). Finally, the paper analyses the rise of a spontaneous cult of Berlinguer at grassroots level over the last thirty years. The kaleidoscopic variety of interpretations regarding Berlinguer’s political legacy is ultimately due to the inability of the Italian post-communist leaders to reconcile themselves with their political past, leading to a splintered and conflictual identity among the Italian post-communist Left in general
Correlations in Hot Asymmetric Nuclear Matter
The single-particle spectral functions in asymmetric nuclear matter are
computed using the ladder approximation within the theory of finite temperature
Green's functions. The internal energy and the momentum distributions of
protons and neutrons are studied as a function of the density and the asymmetry
of the system. The proton states are more strongly depleted when the asymmetry
increases while the occupation of the neutron states is enhanced as compared to
the symmetric case. The self-consistent Green's function approach leads to
slightly smaller energies as compared to the Brueckner Hartree Fock approach.
This effect increases with density and thereby modifies the saturation density
and leads to smaller symmetry energies.Comment: 7 pages, 7 figure
Properties of asymmetric nuclear matter in different approaches
Properties of asymmetric nuclear matter are derived from various many-body
approaches. This includes phenomenological ones like the Skyrme Hartree-Fock
and relativistic mean field approaches, which are adjusted to fit properties of
nuclei, as well as more microscopic attempts like the Brueckner-Hartree-Fock
approximation, a self-consistent Greens function method and the so-called
approach, which are based on realistic nucleon-nucleon interactions
which reproduce the nucleon-nucleon phase shifts. These microscopic approaches
are supplemented by a density-dependent contact interaction to achieve the
empirical saturation property of symmetric nuclear matter. The predictions of
all these approaches are discussed for nuclear matter at high densities in
-equilibrium. Special attention is paid to behavior of the isovector
component of the effective mass in neutron-rich matter.Comment: 16 pages, 7 figure
Non existence of a phase transition for the Penetrable Square Wells in one dimension
Penetrable Square Wells in one dimension were introduced for the first time
in [A. Santos et. al., Phys. Rev. E, 77, 051206 (2008)] as a paradigm for
ultra-soft colloids. Using the Kastner, Schreiber, and Schnetz theorem [M.
Kastner, Rev. Mod. Phys., 80, 167 (2008)] we give strong evidence for the
absence of any phase transition for this model. The argument can be generalized
to a large class of model fluids and complements the van Hove's theorem.Comment: 14 pages, 7 figures, 1 tabl
Nanofriction behavior of cluster-assembled carbon films
We have characterized the frictional properties of nanostructured (ns) carbon
films grown by Supersonic Cluster Beam Deposition (SCBD) via an Atomic
Force-Friction Force Microscope (AFM-FFM). The experimental data are discussed
on the basis of a modified Amonton's law for friction, stating a linear
dependence of friction on load plus an adhesive offset accounting for a finite
friction force in the limit of null total applied load. Molecular Dynamics
simulations of the interaction of the AFM tip with the nanostructured carbon
confirm the validity of the friction model used for this system. Experimental
results show that the friction coefficient is not influenced by the
nanostructure of the films nor by the relative humidity. On the other hand the
adhesion coefficient depends on these parameters.Comment: 22 pages, 6 figures, RevTex
Theoretical and numerical study of the phase diagram of patchy colloids: ordered and disordered patch arrangements
We report theoretical and numerical evaluations of the phase diagram for a
model of patchy particles. Specifically we study hard-spheres whose surface is
decorated by a small number f of identical sites ("sticky spots'') interacting
via a short-range square-well attraction. We theoretically evaluate, solving
the Wertheim theory, the location of the critical point and the gas-liquid
coexistence line for several values of f and compare them to results of Gibbs
and Grand Canonical Monte Carlo simulations. We study both ordered and
disordered arrangements of the sites on the hard-sphere surface and confirm
that patchiness has a strong effect on the phase diagram: the gas-liquid
coexistence region in the temperature-density plane is significantly reduced as
f decreases. We also theoretically evaluate the locus of specific heat maxima
and the percolation line.Comment: preprint, 32 pages, 6 figures, 3 tables, J. Chem. Phys. in pres
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