105 research outputs found
Electric dipole and quadrupole contributions to valence electron binding in a charge-screening environment
We make a multipole expansion of the atomic/molecular electrostatic charge
distribution as seen by the valence electron up to the quadrupole term. The
Tridiagonal Representation Approach (TRA) is used to obtain an exact bound
state solution associated with an effective quadrupole moment and assuming that
the electron-molecule interaction is screened by suborbital electrons. We show
that the number of states available for binding the electron is finite forcing
an energy jump in its transition to the continuum that could be detected
experimentally in some favorable settings. We expect that our solution gives an
alternative, viable and simple description of the binding of valence
electron(s) in atoms/molecules with electric dipole and quadrupole moments. We
also ascertain that our model implies that a pure quadrupole-bound anion cannot
exist in such a charge-screening environment.Comment: 14 pages, 1 tabl
Quantum transport across van der Waals domain walls in bilayer graphene
Bilayer graphene can exhibit deformations such that the two graphene sheets
are locally detached from each other resulting in a structure consisting of
domains with different inter-layer coupling. Here we investigate how the
presence of these domains affect the transport properties of bilayer graphene.
We derive analytical expressions for the transmission probability, and the
corresponding conductance, across walls separating different inter-layer
coupling domain. We find that the transmission can exhibit a valley-dependent
layer asymmetry and that the domain walls have a considerable effect on the
chiral tunnelling properties of the charge carriers. We show that transport
measurements allow one to obtain the strength with which the two layers are
coupled. We performed numerical calculations for systems with two domain walls
and find that the availability of multiple transport channels in bilayer
graphene modifies significantly the conductance dependence on inter-layer
potential asymmetry.Comment: 20 pages, 24 Figure
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