42,029 research outputs found
The dynamic dipole polarizabilities of the Li atom and the Be+ ion
The dynamic dipole polarizabilities for the Li atom and the Be+ ion in the 2s
and 2p states are calculated using the variational method with a Hylleraas
basis. The present polarizabilities represent the definitive values in the
non-relativistic limit. Corrections due to relativistic effects are also
estimated. Analytic representations of the polarizabilities for frequency
ranges encompassing the n=3 excitations are presented. The recommended
polarizabilities for ^7Li and ^9Be+ were 164.11 \pm 0.03 a.u. and 24.489 \pm
0.004 a.u.
Electron-Phonon Interactions for Optical Phonon Modes in Few-Layer Graphene
We present a first-principles study of the electron-phonon (e-ph)
interactions and their contributions to the linewidths for the optical phonon
modes at and K in one to three-layer graphene. It is found that due to
the interlayer coupling and the stacking geometry, the high-frequency optical
phonon modes in few-layer graphene couple with different valence and conduction
bands, giving rise to different e-ph interaction strengths for these modes.
Some of the multilayer optical modes derived from the - mode of
monolayer graphene exhibit slightly higher frequencies and much reduced
linewidths. In addition, the linewidths of K- related modes in
multilayers depend on the stacking pattern and decrease with increasing layer
numbers.Comment: 6 pages,5 figures, submitted to PR
Calculations of polarizabilities and hyperpolarizabilities for the Be ion
The polarizabilities and hyperpolarizabilities of the Be ion in the
state and the state are determined. Calculations are performed
using two independent methods: i) variationally determined wave functions using
Hylleraas basis set expansions and ii) single electron calculations utilizing a
frozen-core Hamiltonian. The first few parameters in the long-range interaction
potential between a Be ion and a H, He, or Li atom, and the leading
parameters of the effective potential for the high- Rydberg states of
beryllium were also computed. All the values reported are the results of
calculations close to convergence. Comparisons are made with published results
where available.Comment: 18 pp; added details to Sec. I
Long-range interactions of metastable helium atoms
Polarizabilities, dispersion coefficients, and long-range atom-surface
interaction potentials are calculated for the n=2 triplet and singlet states of
helium using highly accurate, variationally determined, wave functions.Comment: RevTeX, epsf, 4 fig
A parity-breaking electronic nematic phase transition in the spin-orbit coupled metal CdReO
Strong electron interactions can drive metallic systems toward a variety of
well-known symmetry-broken phases, but the instabilities of correlated metals
with strong spin-orbit coupling have only recently begun to be explored. We
uncovered a multipolar nematic phase of matter in the metallic pyrochlore
CdReO using spatially resolved second-harmonic optical anisotropy
measurements. Like previously discovered electronic nematic phases, this
multipolar phase spontaneously breaks rotational symmetry while preserving
translational invariance. However, it has the distinguishing property of being
odd under spatial inversion, which is allowed only in the presence of
spin-orbit coupling. By examining the critical behavior of the multipolar
nematic order parameter, we show that it drives the thermal phase transition
near 200 kelvin in CdReO and induces a parity-breaking lattice
distortion as a secondary order.Comment: 9 pages main text, 4 figures, 10 pages supplementary informatio
- …