The orbital underpinnings of the electron localization function (ELF), devised by Becke and Edgecombe, are explored in terms of an interpretation of the dominant term in this expression, ρ-5/3∑ i |∇ψ i |2. High ∑ i |∇ψ i |2 implies large electronic kinetic energy and electron delocalization. It is shown how this arises in practice through the population of noded wave functions. Such an approach provides an attractive way with which to view electron localization in systems that obey the Hund localization condition, hypervalent and electron-deficient molecules, and metals and insulators. ELF is shown to provide a description of the term “electron localization” that is highly self-consistent when interpreted in terms of nodes and also consistent with many of the present uses of the term.

We present a trajectory-based method with which to learn information about the qualitative role that solvent molecules play in dynamic simulations of reactions that occur in solution. A spatial grid is superimposed on the system being simulated, and average fluxes of solvent molecules between cells on the grid are calculated along reactive trajectories. The average solvent fluxes form a much smaller set of variables and provide a much simpler description of the reaction under study than the full list of atomic positions and momenta. The feasibility and utility of the method are demonstrated by producing reduced descriptions of the mechanisms of the dissociation reaction of NaCl in water and of the rearrangement of the alanine dipeptide in water. Comparisons between our method and other possible data reduction techniques are discussed.

Density functional calculations were performed on 1,1‘,5,5‘-tetramethyl-6,6‘-dioxo-3,3‘-biverdazyl diradical (BVD) and BVD[CuI(PL3)]2 complexes (L = H, Me, OH, OMe, F) in order to investigate how Cu chelation affects the singlet−triplet splitting of the verdazyl system. It was found that donating ligands on Cu destabilize the singlet ground state. Size was also found to play a role, as smaller ligands allow for closer Cu−verdazyl contacts. Although a triplet ground state was not obtained for any of the molecules examined, a very small splitting of 40 cm-1 was calculated for the phosphine complex.

This cohort study assesses whether removal of a warning against use of cephalosporins in the electronic health record (EHR) of patients with penicillin allergy was associated with changes in the dispensing or administration of cephalosporins.

A lattice gas simulation of water between a hydrophobic plate and a hydrophilic plate (a Janus interface) shows large fluctuations in the number of liquid cells in contact with the hydrophobic plate, and a power spectrum similar to the experimental results that Zhang, Zhu, and Granick found [X. Y. Zhang, Y. X. Zhu, and S. Granick, Science 295, 663 (2002)] when measuring viscous response in a Janus system. Study of the spatial Fourier modes of the liquid-vapor interface suggests that interface fluctuations with length scales between approximately 1.5 and 20 nm cause the effects observed in the simulation.