Most resonant inelastic x-ray scattering (RIXS) studies of dynamic charge order correlations in the cuprates have focused on the high-symmetry directions of the copper oxide plane. However, scattering along other in-plane directions should not be ignored as it may help understand, for example, the origin of charge order correlations or the isotropic scattering resulting in strange metal behavior. Our RIXS experiments reveal dynamic charge correlations over the
q
x
-q
y
scattering plane in underdoped Bi
2
Sr
2
CaCu
2
O
8+δ
. Tracking the softening of the RIXS-measured bond-stretching phonon, we show that these dynamic correlations exist at energies below approximately 70 meV and are centered around a quasi-circular manifold in the
q
x
-q
y
scattering plane with radius equal to the magnitude of the charge order wave vector,
q
CO
. This phonon-tracking procedure also allows us to rule out fluctuations of short-range directional charge order (i.e., centered around [
q
x
= ±
q
CO
,
q
y
= 0] and [
q
x
= 0,
q
y
= ±
q
CO
]) as the origin of the observed correlations.
We used density functional theory to examine the effects impurities and vacancies in the dilute limit in order to explore the effects on the local structure of the unalloyed face centered cubic δ-Pu lattice. The impurities considered are the radioactive daughter U or stabilizers in δ-phase stabilizer Ga. These impurities were placed at various interstitial sites, including octahedral, tetrahedral, and split interstitial along the (100) direction, as well as substitutional lattice sites. Self-interstitials, mono and di-vacancies were also considered. In addition we examined impurity-vacancy complexes at first and second nearest neighboring distances from each other. Radial distribution functions were plotted to gauge the local structural variations around the defect within the lattice and volume change with structural variation quantifies influence on thermodynamics. These local distortions will be discussed in this report.
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