63,989 research outputs found
Calculation of accurate permanent dipole moments of the lowest states of heteronuclear alkali dimers using extended basis sets
The obtention of ultracold samples of dipolar molecules is a current
challenge which requires an accurate knowledge of their electronic properties
to guide the ongoing experiments. In this paper, we systematically investigate
the ground state and the lowest triplet state of mixed alkali dimers (involving
Li, Na, K, Rb, Cs) using a standard quantum chemistry approach based on
pseudopotentials for atomic core representation, gaussian basis sets, and
effective terms for core polarization effects. We emphasize on the convergence
of the results for permanent dipole moments regarding the size of the gaussian
basis set, and we discuss their predicted accuracy by comparing to other
theoretical calculations or available experimental values. We also revisit the
difficulty to compare computed potential curves among published papers, due to
the differences in the modelization of core-core interaction.Comment: accepted to J. Chem. Phy
Constraints on Hidden Photon Models from Electron g-2 and Hydrogen Spectroscopy
The hidden photon model is one of the simplest models which can explain the
anomaly of the muon anomalous magnetic moment (g-2). The experimental
constraints are studied in detail, which come from the electron g-2 and the
hydrogen transition frequencies. The input parameters are set carefully in
order to take dark photon contributions into account and to prevent the
analysis from being self-inconsistent. It is shown that the new analysis
provides a constraint severer by more than one order of magnitude than the
previous result.Comment: 18 pages, 2 figures, 1 table. v2: minor correction
Luttinger liquid physics from infinite-system DMRG
We study one-dimensional spinless fermions at zero and finite temperature T
using the density matrix renormalization group. We consider nearest as well as
next-nearest neighbor interactions; the latter render the system inaccessible
by a Bethe ansatz treatment. Using an infinite-system alogrithm we demonstrate
the emergence of Luttinger liquid physics at low energies for a variety of
static correlation functions as well as for thermodynamic properties. The
characteristic power law suppression of the momentum distribution n(k) function
at T=0 can be directly observed over several orders of magnitude. At finite
temperature, we show that n(k) obeys a scaling relation. The Luttinger liquid
parameter and the renormalized Fermi velocity can be extracted from the density
response function, the specific heat, and/or the susceptibility without the
need to carry out any finite-size analysis. We illustrate that the energy scale
below which Luttinger liquid power laws manifest vanishes as the half-filled
system is driven into a gapped phase by large interactions
Lattice-induced non-adiabatic frequency shifts in optical lattice clocks
We consider the frequency shift in optical lattice clocks which arises from
the coupling of the electronic motion to the atomic motion within the lattice.
For the simplest of 3-D lattice geometries this coupling is shown to only
affect clocks based on blue-detuned lattices. We have estimated the size of
this shift for the prospective strontium lattice clock operating at the 390 nm
blue-detuned magic wavelength. The resulting fractional frequency shift is
found to be on the order of and is largely overshadowed by the
electric quadrupole shift. For lattice clocks based on more complex geometries
or other atomic systems, this shift could potentially be a limiting factor in
clock accuracy.Comment: 5 page
Approaching Many-Body Localization from Disordered Luttinger Liquids via the Functional Renormalization Group
We study the interplay of interactions and disorder in a one-dimensional
fermion lattice coupled adiabatically to infinite reservoirs. We employ both
the functional renormalization group (FRG) as well as matrix product state
techniques, which serve as an accurate benchmark for small systems. Using the
FRG, we compute the length- and temperature-dependence of the conductance
averaged over samples for lattices as large as sites. We
identify regimes in which non-ohmic power law behavior can be observed and
demonstrate that the corresponding exponents can be understood by adapting
earlier predictions obtained perturbatively for disordered Luttinger liquids.
In presence of both disorder and isolated impurities, the conductance has a
universal single-parameter scaling form. This lays the groundwork for an
application of the functional renormalization group to the realm of many-body
localization
Calculation of the energy levels of Ge, Sn, Pb and their ions in the approximation
Energy levels of germanium, tin and lead together with their single, double
and triple ionized positive ions have been calculated using the
approximation suggested in the previous work (Dzuba, physics/0501032) (M=4 -
number of valence electrons). Initial Hartree-Fock calculations are done for
the quadruply ionized ions with all valence electrons removed. The core-valence
correlations are included beyond the second-order of the many-body perturbation
theory. Interaction between valence electrons is treated by means of the
configuration interaction technique. It is demonstrated that accurate treatment
of the core-valence correlations lead to systematic improvement of the accuracy
of calculations for all ions and neutral atoms.Comment: 7 pages, 3 figures, 3 tables; submitted to Phys. Rev.
Development of Beluga, Delphinapterus leucas, Capture and Satellite Tagging Protocol in Cook Inlet, Alaska
Attempts to capture and place satellite tags on belugas, Delphinapterus leucas, in Cook Inlet, Alaska were conducted during late spring and summer of 1995, 1997, and 1999. In 1995, capture attempts using a hoop net proved impractical in Cook Inlet. In 1997, capture efforts focused on driving belugas into nets. Although this method had been successful in the Canadian High Arctic, it failed in Cook Inlet due to the ability of the whales to detect and avoid nets in shallow and very turbid water. In 1999, belugas were successfully captured using a gillnet encirclement technique. A satellite tag was attached to a juvenile male, which subsequently provided the first documentation of this species’ movements within Cook Inlet during the summer months (31 May–17 September)
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