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1. Density-Corrected Density Functional Theory for Molecular Properties

   https://doi.org/10.1021/acs.jpclett.3c00953  

   Morgante, Pierpaolo ; Autschbach, Jochen ( June 2023 , The Journal of Physical Chemistry Letters)
2. Comparison of Density-Matrix Corrections to Density Functional Theory

   https://doi.org/10.1021/acs.jctc.2c00625  

   Gibney, Daniel ; Boyn, Jan-Niklas ; Mazziotti, David A. ( November 2022 , Journal of Chemical Theory and Computation)
3. Density Stratification and Buoyancy Evolution in Pyroclastic Density Currents

   https://doi.org/10.1029/2024JB029208  

   O’Donnell, Sean_B ; Johnson, Blair_A ; Breard, Eric_C_P ; Buttles, James_L ; Gardner, James_E ; Mohrig, David ; Dufek, Josef ( June 2024 , Journal of Geophysical Research: Solid Earth)

   Pyroclastic density currents (PDCs) are density‐stratified along their vertical axis, with the near‐bed portion being denser than the upper portion, resulting from particle settling and ambient air entrainment at current margins. Whereas vertical density stratification likely influences mixing, sedimentation, and buoyancy of PDCs, many depth‐averaged models of PDC dynamics assume currents are well‐mixed. We investigated this discrepancy by performing sub‐aqueous laboratory experiments and conducted complementary numerical simulations to interrogate current dynamics at finer scales. Currents with small temperature difference with the ambient fluid become density‐stratified during propagation. The dynamics of such currents resemble two‐phase flows, in which particles move freely and particle concentration becomes stratified, but fluid density remains constant. Currents with large temperature difference with the ambient fluid, however, do not develop density stratification during propagation, due to current dynamics becoming dominated by the fluid phase and the lessening importance of particles. Currents that develop density stratification do not lift off from the bed within the domain of the setup, whereas poorly stratified currents do lift off, forming a rising plume. Strong density stratification within currents inhibits turbulence production, preventing entrained ambient fluid on current edges from mixing into current interiors. Poorly stratified currents are highly turbulent, have vigorous internal mixing, thereby achieving lift‐off. The strongly stratified currents are analogous to PDCs that result from eruption column collapse, maintaining fast velocity, low internal mixing, and high temperature over long distances. The poorly stratified currents are analogous to dilute ash‐cloud surges that develop atop basal avalanches, having short runout distances.

    

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4. Improving Results by Improving Densities: Density-Corrected Density Functional Theory

   https://doi.org/10.1021/jacs.1c11506  

   Sim, Eunji ; Song, Suhwan ; Vuckovic, Stefan ; Burke, Kieron ( April 2022 , Journal of the American Chemical Society)
5. Density-dependent adult recruitment in a low-density tropical tree

   https://doi.org/10.1073/pnas.1800353115  

   Kellner, James R. ; Hubbell, Stephen P. ( October 2018 , Proceedings of the National Academy of Sciences)

   The Janzen–Connell hypothesis is a well-known explanation for why tropical forests have large numbers of tree species. A fundamental prediction of the hypothesis is that the probability of adult recruitment is less in regions of high conspecific adult density, a pattern mediated by density-dependent mortality in juvenile life stages. Although there is strong evidence in many tree species that seeds, seedlings, and saplings suffer conspecific density-dependent mortality, no study has shown that adult tree recruitment is negatively density dependent. Density-dependent adult recruitment is necessary for the Janzen–Connell mechanism to regulate tree populations. Here, we report density-dependent adult recruitment in the population ofHandroanthus guayacan, a wind-dispersed Neotropical canopy tree species. We use data from high-resolution remote sensing to track individual trees with proven capacity to flower in a lowland moist forest landscape in Panama and analyze these data in a Bayesian framework similar to capture–recapture analysis. We independently quantify probabilities of adult tree recruitment and detection and show that adult recruitment is negatively density dependent. The annualized probability of adult recruitment was 3.03% ⋅ year⁻¹. Despite the detection of negative density dependence in adult recruitment, it was insufficient to stabilize the adult population ofH. guayacan, which increased significantly in size over the decade of observation.

    

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