10,100 research outputs found
Density of states of a binary Lennard-Jones Glass
We calculate the density of states of a binary Lennard-Jones glass using a
recently proposed Monte Carlo algorithm. Unlike traditional molecular
simulation approaches, the algorithm samples distinct configurations according
to self-consistent estimates of the density of states, thereby giving rise to
uniform internal-energy histograms. The method is applied to simulate the
equilibrium, low-temperature thermodynamic properties of a widely studied glass
former consisting of a binary mixture of Lennard-Jones particles. We show how a
density-of-states algorithm can be combined with particle identity swaps and
configurational bias techniques to study that system. Results are presented for
the energy and entropy below the mode coupling temperature.Comment: 6 pages, 3 figures, accepted by J Chem Phy
Constant Pressure Hybrid Molecular Dynamics-Monte Carlo Simulations
New hybrid Molecular Dynamics-Monte Carlo methods are proposed to increase
the efficiency of constant-pressure simulations. Two variations of the isobaric
Molecular Dynamics component of the algorithms are considered. In the first, we
use the extended-ensemble method of Andersen [H. C. Andersen J. Chem. Phys.
{\bf 72},2384 (1980)]. In the second, we arrive at a new constant-pressure
Monte Carlo technique based on the reversible generalization of the
weak-coupling barostat [H. J. C. Berendsen et. al J. Chem. Phys. {\bf 81},
3684(1984)]. This latter technique turns out to be highly effective in
equilibrating and maintaining a target pressure. It is superior to the
extended-ensemble method, which in turn is superior to simple volume-rescaling
algorithms. The efficiency of the proposed methods is demonstrated by studying
two systems. The first is a simple Lennard-Jones fluid. The second is a mixture
of polyethylene chains of 200 monomers.Comment: 10 pages, 4 figure
Density of States Monte Carlo Method for Simulation of Fluids
A Monte Carlo method based on a density-of-states sampling is proposed for
study of arbitrary statistical mechanical ensembles in a continuum. A random
walk in the two-dimensional space of particle number and energy is used to
estimate the density of states of the system; this density of states is
continuously updated as the random walk visits individual states. The validity
and usefulness of the method are demonstrated by applying it to the simulation
of a Lennard-Jones fluid. Results for its thermodynamic properties, including
the vapor-liquid phase coexistence curve, are shown to be in good agreement
with high-accuracy literature data.Comment: 5 pages, 3 figures, accepted by J Chem Phy
Corruption and entrepreneurship: A bibliometric analysis
The impact of corruption on entrepreneurial dynamics became an attractive topic for scholars after the appearance of public scandals that led to the delegitimization of many governments in the last 40 years. The research that explored the relationship between corruption and entrepreneurship has produced controversial results. It appears that the interaction of these two constructs is influenced by contextual factors both at an individual and national level of analysis. By using a bibliometric methodology and a fractional counting method to analyse the scientific literature on corruption and entrepreneurship, this paper identifies and analyses 180 articles recorded in the Scopus database. It represents a contribution by showing the state of the art of research on corruption and entrepreneurship and proposes future lines of research. Important results have been found about the evolution of the volume of articles and citations on this topic over time. Significant academic interest in this field commenced in the 21st century, and more specifically in the last ten years. This work also provides findings about the most prolific journals, institutions and authors, as well as the most relevant countries, with the United States and United Kingdom leading in terms of the number of publications. In addition, an in-depth analysis of authors' keywords has identified different trends, such as institutions, economic growth, shadow economy, regulation, Africa, culture, economic development, business environment, and informal economy. Finally, some future research lines are proposed, such as institutional theory, tax morale, corruption perceptions, European regions, risk aversion and institutional entrepreneurship
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