105,599 research outputs found
CARS spectroscopy of the () band in
Molecular hydrogen is a benchmark system for bound state quantum calculation
and tests of quantum electrodynamical effects. While spectroscopic measurements
on the stable species have progressively improved over the years, high
resolution studies on the radioactive isotopologues , and
have been limited. Here we present an accurate determination of
transition energies in the fundamental vibrational
band of the ground electronic state, by means of high resolution Coherent
Anti-Stokes Raman Spectroscopy. With the present experimental uncertainty of
, which is a fivefold improvement over previous
measurements, agreement with the latest theoretical calculations is
demonstrated.Comment: 9 pages, 3 figure
Topology and Interactions in a Frustrated Slab: Tuning from Weyl Semimetals to C > 1 Fractional Chern Insulators
We show that, quite generically, a [111] slab of spin-orbit coupled
pyrochlore lattice exhibits surface states whose constant energy curves take
the shape of Fermi arcs, localized to different surfaces depending on their
quasimomentum. Remarkably, these persist independently of the existence of Weyl
points in the bulk. Considering interacting electrons in slabs of finite
thickness, we find a plethora of known fractional Chern insulating phases, to
which we add the discovery of a new higher Chern number state which is likely a
generalization of the Moore-Read fermionic fractional quantum Hall state. By
contrast, in the three-dimensional limit, we argue for the absence of gapped
states of the flat surface band due to a topologically protected coupling of
the surface to gapless states in the bulk. We comment on generalizations as
well as experimental perspectives in thin slabs of pyrochlore iridates.Comment: Published. 6+4 page
Oxygen-isotope effect on the in-plane penetration depth in underdoped Y_{1-x}Pr_xBa_2Cu_3O_{7-delta} as revealed by muon-spin rotation
The oxygen-isotope (^16O/^18O) effect (OIE) on the in-plane penetration depth
in underdoped Y_{1-x}Pr_xBa_2Cu_3O_{7-delta} was studied by
muon-spin rotation. A pronounced OIE on was observed
with a relative isotope shift of
=-5(2)% for x =0.3 and -9(2)% for
x=0.4. It arises mainly from the oxygen-mass dependence of the in-plane
effective mass . The OIE exponents of T_{c} and of
exhibit a relation that appears to be generic for
cuprate superconductors.Comment: 4 pages, 4 eps figures, RevTex
Tensor-Structured Coupled Cluster Theory
We derive and implement a new way of solving coupled cluster equations with
lower computational scaling. Our method is based on decomposition of both
amplitudes and two electron integrals, using a combination of tensor
hypercontraction and canonical polyadic decomposition. While the original
theory scales as with respect to the number of basis functions, we
demonstrate numerically that we achieve sub-millihartree difference from the
original theory with scaling. This is accomplished by solving directly
for the factors that decompose the cluster operator. The proposed scheme is
quite general and can be easily extended to other many-body methods
Projected Coupled Cluster Theory: Optimization of cluster amplitudes in the presence of symmetry projection
Methods which aim at universal applicability must be able to describe both
weak and strong electronic correlation with equal facility. Such methods are in
short supply. The combination of symmetry projection for strong correlation and
coupled cluster theory for weak correlation offers tantalizing promise to
account for both on an equal footing. In order to do so, however, the coupled
cluster portion of the wave function must be optimized in the presence of the
symmetry projection. This paper discusses how this may be accomplished, and
shows the importance of doing so for both the Hubbard model Hamiltonian and the
molecular Hamiltonian, all with a computational scaling comparable to that of
traditional coupled cluster theory.Comment: revised versio
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