2,667 research outputs found
Microscopic two-fluid theory of rotational constants of the OCS-H complex in He droplets
We present a microscopic quantum analysis for rotational constants of the
OCS-H complex in helium droplets using the local two-fluid theory in
conjunction with path integral Monte Carlo simulations. Rotational constants
are derived from effective moments of inertia calculated assuming that motion
of the H molecule and the local non-superfluid helium density is rigidly
coupled to the molecular rotation of OCS and employing path integral methods to
sample the corresponding H and helium densities. The rigid coupling
assumption for H-OCS is calibrated by comparison with exact calculations of
the free OCS-H complex. The presence of the H molecule is found to
induce a small local non-superfluid helium density in the second solvation
shell which makes a non-negligible contribution to the moment of inertia of the
complex in helium. The resulting moments of inertia for the OCS-H complex
embedded in a cluster of 63 helium atoms are found to be in good agreement with
experimentally measured values in large helium droplets. Implications for
analysis of rotational constants of larger complexes of OCS with multiple H
molecules in helium are discussed.Comment: 11 pages, 5 figures, accepted for publication in J. Chem. Phy
Dynamical Mean-Field Theory Simulations with the Adaptive Sampling Configuration Interaction Method
In the pursuit of accurate descriptions of strongly correlated quantum
many-body systems, dynamical mean-field theory (DMFT) has been an invaluable
tool for elucidating the spectral properties and quantum phases of both
phenomenological models and ab initio descriptions of real materials. Key to
the DMFT process is the self-consistent map of the original system into an
Anderson impurity model, the ground state of which is computed using an
impurity solver. The power of the method is thus limited by the complexity of
the impurity model the solver can handle. Simulating realistic systems
generally requires many correlated sites. By adapting the recently proposed
adaptive sampling configuration interaction (ASCI) method as an impurity
solver, we enable much more efficient zero temperature DMFT simulations. The
key feature of the ASCI method is that it selects only the most relevant
Hilbert space degrees of freedom to describe the ground state. This reduces the
numerical complexity of the calculation, which will allow us to pursue future
DMFT simulations with more correlated impurity sites than in previous works.
Here we present the ASCI-DMFT method and example calculations on the
one-dimensional and two-dimensional Hubbard models that exemplify its efficient
convergence and timing properties. We show that the ASCI approach is several
orders of magnitude faster than the current best published ground state DMFT
simulations, which allows us to study the bath discretization error in
simulations with small clusters, as well as to address cluster sizes beyond the
current state of the art. Our approach can also be adapted for other embedding
methods such as density matrix embedding theory and self-energy embedding
theory.Comment: 12 pages, 11 figures, supplemental informatio
THE LONG VOYAGE HOME
This research paper (βPaperβ) examines the international, constitutional, legal history, and current rights to housing in the United States (U.S.), Jamaica, and South Africa. This Paper addresses the federal and sub-national systems regarding affordable housing initiatives that drive policies associated with poverty and homelessness. Moreover, the following thesis addresses the need for affordable housing and discusses the substantive right to housing. It examines the legal avenues and obstacles that must be overcome given the division of powers in each country. This Paper will discuss significant influences such as colonialism that shape current housing policies to eradicate poverty and homelessness. Colonial domination has triggered tremendous changes economically in the U.S. while others have remained disenfranchised (Jamaica and South Africa). This Paper calls for a transformed focus on housing law and poverty, specifically in the housing sector where low-income families live
An Application of Word Sense Disambiguation to Information Retrieval
The problems of word sense disambiguation and document indexing for information retrieval have been extensively studied. It has been observed that indexing using disambiguated meanings, rather than word stems, should improve information retrieval results. We present a new corpus-based algorithm for performing word sense disambiguation. The algorithm does not need to train on many senses of each word; it uses instead the probability that certain concepts will occur together. That algorithm is then used to index several corpa of documents. Our indexing algorithm does not generally outperform the traditional stem-based tf.idf model
Stable quantum memories with limited measurement
We demonstrate the existence of a finite temperature threshold for a 1D
stabilizer code under an error correcting protocol that requires only a
fraction of the syndrome measurements. Below the threshold temperature, encoded
states have exponentially long lifetimes, as demonstrated by numerical and
analytical arguments. We sketch how this algorithm generalizes to higher
dimensional stabilizer codes with string-like excitations, like the toric code.Comment: 11 Pages, 7 Figure
- β¦