2,701 research outputs found
Collective Modes of Massive Dirac Fermions in Armchair Graphene Nanoribbons
We report the plasmon dispersion characteristics of intrinsic and extrinsic
armchair graphene nanoribbons of atomic width N = 5 using a p_z-orbital tight
binding model with third-nearest-neighbor (3nn) coupling. The coupling
parameters are obtained by fitting the 3nn dispersions to that of an extended
Huckel theory. The resultant massive Dirac Fermion system has a band gap E_g
\approx 64 meV. The extrinsic plasmon dispersion relation is found to approach
a common dispersion curve as the chemical potential increases, whereas
the intrinsic plasmon dispersion relation is found to have both energy and
momentum thresholds. We also report an analytical model for the extrinsic
plasmon group velocity in the q \rightarrow 0 limit
The rent's too high: Self-archive for fair online publication costs
The main contributors of scientific knowledge, researchers, generally aim to
disseminate their findings far and wide. And yet, publishing companies have
largely kept these findings behind a paywall. With digital publication
technology markedly reducing cost, this enduring wall seems disproportionate
and unjustified; moreover, it has sparked a topical exchange concerning how to
modernize academic publishing. This discussion, however, seems to focus on how
to compensate major publishers for providing open access through a "pay to
publish" model, in turn transferring financial burdens from libraries to
authors and their funders. Large publishing companies, including Elsevier,
Springer Nature, Wiley, PLoS, and Frontiers, continue to earn exorbitant
revenues each year, hundreds of millions of dollars of which now come from
processing charges for open-access articles. A less expensive and equally
accessible alternative exists: widespread self-archiving of peer-reviewed
articles. All we need is awareness of this alternative and the will to employ
itComment: 8 pages, 1 figure, 19 reference
An Extended Huckel Theory based Atomistic Model for Graphene Nanoelectronics
An atomistic model based on the spin-restricted extended Huckel theory (EHT)
is presented for simulating electronic structure and I-V characteristics of
graphene devices. The model is applied to zigzag and armchair graphene
nano-ribbons (GNR) with and without hydrogen passivation, as well as for
bilayer graphene. Further calculations are presented for electric fields in the
nano-ribbon width direction and in the bilayer direction to show electronic
structure modification. Finally, the EHT Hamiltonian and NEGF (Nonequilibrium
Green's function) formalism are used for a paramagnetic zigzag GNR to show
2e2/h quantum conductance.Comment: 5 pages, 8 figure
A Critical Analysis of Chromotherapy and Its Scientific Evolution
Chromotherapy is a method of treatment that uses the visible spectrum (colors) of electromagnetic radiation to cure diseases. It is a centuries-old concept used successfully over the years to cure various diseases. We have undertaken a critical analysis of chromotherapy and documented its scientific evolution to date. A few researchers have tried to discover the underlying scientific principles, but without quantitative study. Sufficient published material can be found about the subject that provides a complete system of treatment focused on the treatment methodologies and healing characteristics of colors. A number of studies have elaborated the relationship between the human body and colors. We also show the possibility of carrying out diverse research into chromotherapy that is pertinent to deciphering the quantum mechanical dipole moment of water molecules. The quantum mechanical dipole moment as a result of the absorption of different colors, we conjecture, produces charge quantization phenomena. This review illustrates that the development of science in the field of electromagnetic radiation/energy can be very helpful in discovering new dimensions of this old theory
Onshore to near-shore outsourcing transitions: unpacking tensions
This study is directed towards highlighting tensions of incoming and outgoing vendors during outsourcing in a near-shore context. Incoming-and-outgoing of vendors generate a complex form of relationship in which the participating organizations cooperate and compete simultaneously. It is of great importance to develop knowledge about this kind of relationship typically in the current GSE-related multi-sourcing environment. We carried out a longitudinal case study and utilized data from the 'Novo pay' project, which is available in the public domain. This project involved an outgoing New Zealand based vendor and incoming Australian based vendor. The results show that the demand for the same human resources, dependency upon cooperation and collaboration between vendors, reliance on each other system's configurations and utilizing similar strategies by the client, which worked for the previous vendor, generated a set of tensions which needed to be continuously managed throughout the project
Strain and field modulation in bilayer graphene band structure
Using an external electric field, one can modulate the bandgap of Bernal
stacked bilayer graphene by breaking A-~B symmetry. We analyze strain effects
on the bilayer graphene using the extended Huckel theory and find that reduced
interlayer distance results in higher bandgap modulation, as expected.
Furthermore, above about 2.5 angstrom interlayer distance, the bandgap is
direct, follows a convex relation to electric field and saturates to a value
determined by the interlayer distance. However, below about 2.5 angstrom, the
bandgap is indirect, the trend becomes concave and a threshold electric field
is observed, which also depends on the stacking distance.Comment: 3 pages, 5 figures - v1 and v2 are the same, uploaded twice - v3,
some typos fixed and a reference adde
Theoretical study of isolated dangling bonds, dangling bond wires and dangling bond clusters on H:Si(100)-(21) surface
We theoretically study the electronic band structure of isolated unpaired and
paired dangling bonds (DB), DB wires and DB clusters on H:Si(100)-(21)
surface using Extended H\"uckel Theory (EHT) and report their effect on the Si
band gap. An isolated unpaired DB introduces a near-midgap state, whereas a
paired DB leads to and states, similar to those introduced by an
unpassivated asymmetric dimer (AD) Si(100)-(21) surface. Such induced
states have very small dispersion due to their isolation from the other states,
which reside in conduction and valence band. On the other hand, the surface
state induced due to an unpaired DB wire in the direction along the dimer row
(referred to as ), has large dispersion due to the strong coupling
between the adjacent DBs, being 3.84 apart. However, in the direction
perpendicular to the dimer row (referred to as [110]), due to the reduced
coupling between the DBs being 7.68 apart, the dispersion in the surface
state is similar to that of an isolated unpaired DB. Apart from this, a paired
DB wire in direction introduces and states similar
to those of an AD surface and a paired DB wire in [110] direction exhibits
surface states similar to those of an isolated paired DB, as expected. Besides
this, we report the electronic structure of different DB clusters, which
exhibit states inside the band gap that can be interpreted as superpositions of
states due to unpaired and paired DBs.Comment: 7 pages, 10 figure, 1 tabl
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