3,936 research outputs found
Electronic, mechanical, and thermodynamic properties of americium dioxide
By performing density functional theory (DFT) + calculations, we
systematically study the electronic, mechanical, tensile, and thermodynamic
properties of AmO. The experimentally observed antiferromagnetic
insulating feature [J. Chem. Phys. 63, 3174 (1975)] is successfully reproduced.
It is found that the chemical bonding character in AmO is similar to that
in PuO, with smaller charge transfer and stronger covalent interactions
between americium and oxygen atoms. The valence band maximum and conduction
band minimum are contributed by 2 hybridized and 5 electronic states
respectively. The elastic constants and various moduli are calculated, which
show that AmO is less stable against shear forces than PuO. The
stress-strain relationship of AmO is examined along the three low-index
directions by employing the first-principles computational tensile test method.
It is found that similar to PuO, the [100] and [111] directions are the
strongest and weakest tensile directions, respectively, but the theoretical
tensile strengths of AmO are smaller than those of PuO. The phonon
dispersion curves of AmO are calculated and the heat capacities as well
as lattice expansion curve are subsequently determined. The lattice thermal
conductance of AmO is further evaluated and compared with attainable
experiments. Our present work integrally reveals various physical properties of
AmO and can be referenced for technological applications of AmO
based materials.Comment: 23 pages, 8 figure
Nondeterminstic ultrafast ground state cooling of a mechanical resonator
We present an ultrafast feasible scheme for ground state cooling of a
mechanical resonator via repeated random time-interval measurements on an
auxiliary flux qubit. We find that the ground state cooling can be achieved
with \emph{several} such measurements. The cooling efficiency hardly depends on
the time-intervals between any two consecutive measurements. The scheme is also
robust against environmental noises.Comment: 4 pages, 3 figure
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