19,504 research outputs found
Chemical Hardness, Linear Response, and Pseudopotential Transferability
We propose a systematic method of analyzing pseudopotential transferability
based on linear-response properties of the free atom, including self-consistent
chemical hardness and polarizability. Our calculation of hardness extends the
approach of Teter\cite{teter} not only by including self-consistency, but also
by generalizing to non-diagonal hardness matrices, thereby allowing us to test
for transferability to non-spherically symmetric environments. We apply the
method to study the transferability of norm-conserving pseudopotentials for a
variety of elements in the Periodic Table. We find that the self-consistent
corrections are frequently significant, and should not be neglected. We prove
that the partial-core correction improves the pseudopotential hardness of
alkali metals considerably. We propose a quantity to represent the average
hardness error and calculate this quantity for many representative elements as
a function of pseudopotential cutoff radii. We find that the atomic
polarizabilities are usually well reproduced by the norm-conserving
pseudopotentials. Our results provide useful guidelines for making optimal
choices in the pseudopotential generation procedure.Comment: Revtex (preprint style, 33 pages) + 9 postscript figures A version in
two-column article style with embedded figures is available at
http://electron.rutgers.edu/~dhv/preprints/index.html#l
Extra Dimensions: A View from the Top
In models with compact extra dimensions, where the Standard Model fields are
confined to a 3+1 dimensional hyperplane, the production
cross-section at a hadron collider can receive significant contributions from
multiple exchange of KK modes of the graviton. These are carefully computed in
the well-known ADD and RS scenarios, taking the energy dependence of the sum
over graviton propagators into account. Using data from Run-I of the Tevatron,
95% C.L. bounds on the parameter space of both models are derived. For Run-II
of the Tevatron and LHC, discovery limits are estimated.Comment: Typos corrected, references added. 12 pages, LaTeX, 2 ps figure
Multiparty Quantum Secret Sharing Based on Entanglement Swapping
A multiparty quantum secret sharing (QSS) protocol is proposed by using
swapping quantum entanglement of Bell states. The secret messages are imposed
on Bell states by local unitary operations. The secret messages are split into
several parts and each part is distributed to a party so that no action of a
subset of all the parties but their entire cooperation is able to read out the
secret messages. In addition, the dense coding is used in this protocol to
achieve a high efficiency. The security of the present multiparty QSS against
eavesdropping has been analyzed and confirmed even in a noisy quantum channel.Comment: 5 page
Optimization of robustness of scale-free network to random and targeted attacks
The scale-fee networks, having connectivity distribution (where is the site connectivity), is very resilient to random
failures but fragile to intentional attack. The purpose of this paper is to
find the network design guideline which can make the robustness of the network
to both random failures and intentional attack maximum while keeping the
average connectivity per node constant. We find that when $=3$ the
robustness of the scale-free networks reach its maximum value if the minimal
connectivity $m=1$, but when is larger than four, the networks will
become more robust to random failures and targeted attacks as the minimal
connectivity gets larger
Nuclear Modification to Parton Distribution Functions and Parton Saturation
We introduce a generalized definition of parton distribution functions (PDFs)
for a more consistent all-order treatment of power corrections. We present a
new set of modified DGLAP evolution equations for nuclear PDFs, and show that
the resummed -type of leading nuclear size enhanced power
corrections significantly slow down the growth of gluon density at small-.
We discuss the relation between the calculated power corrections and the
saturation phenomena.Comment: 4 pages, to appear in the proceedings of QM200
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