181 research outputs found
Exactly solvable -symmetric models in two dimensions
Non-hermitian, -symmetric Hamiltonians, experimentally realized
in optical systems, accurately model the properties of open, bosonic systems
with balanced, spatially separated gain and loss. We present a family of
exactly solvable, two-dimensional, potentials for a
non-relativistic particle confined in a circular geometry. We show that the
symmetry threshold can be tuned by introducing a second
gain-loss potential or its hermitian counterpart. Our results explicitly
demonstrate that breaking in two dimensions has a rich phase
diagram, with multiple re-entrant symmetric phases.Comment: 6 pages, 6 figure
Atomic Compton profiles within different exchange-only theories
The Impulse Compton Profiles (CP's) J(q) and the - expectation values
for some inert gas atoms (He-Kr) are computed and compared within the
Harbola-Sahni (HS), Hartree-Fock(HF) theories and a Self Interaction Corrected
(SIC) density functional model. The Compton profiles for excited states of
Helium atom are also calculated. While the calculated CP's are found to
generally agree, they differ slightly from one another for small values of the
Compton parameter q and are in good agreement for large q values. The
expectation values within the three theories are also found to be comparable.
The HS formalism seem to mimic HF reasonably well in the momentum space,
establishing the logical consistency of the former.Comment: 15 page
Strain-induced stabilization of Al functionalization in graphene oxide nanosheet for enhanced NH3 storage
Strain effects on the stabilization of Al ad-atom on graphene
oxide(GO)nanosheet as well as its implications for NH3 storage have been
investigated using first-principles calculations.The binding energy of Al
ad-atom on GO is found to be a false indicator of its stability.Tensile strain
is found to be very effective in stabilizing the Al ad-atom on GO.It
strengthens the C-O bonds through an enhanced charge transfer from C to O
atoms. Interestingly,C-O bond strength is found to be the correct index for
Al's stability.Optimally strained Al-functionalized GO binds up to 6 NH3
molecules,while it binds no NH3 molecule in unstrained condition.Comment: 11 pages, 3 figures, 4 tables, Applied Physics Letters (Under Review
Momentum space properties from coordinate space electron density
Electron density and electron momentum density, while independently tractable
experimentally, bear no direct connection without going through the
many-electron wave function. However, invoking a variant of the
constrained-search formulation of density functional theory, we develop a
general scheme (valid for arbitrary external potentials) yielding decent
momentum space properties, starting exclusively from the coordinate space
electron density. Numerical illustration of the scheme is provided for the
closed-shell atomic systems He, Be and Ne and for singlet
electronic excited state for Helium by calculating the Compton profiles and the
expectation values derived from given coordinate space electron
densities.Comment: 4 pages, 1 figur
Nonexistence of local maxima in molecular electrostatic potential maps
It has been rigorously established by means of classical electrostatic arguments, that molecular electrostatic potential maps are devoid of local maxima. This forms a generalization of the earlier works of Politzer and co-workers which were restricted to the case of atoms
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