Mott transition and pseudogap of the square-lattice Hubbard model: results from center-focused cellular dynamical mean-field theory

The recently proposed center-focused post-processing procedure [Phys. Rev. Research 2, 033476 (2020)] of cellular dynamical mean-field theory suggests that central sites of large impurity clusters are closer to the exact solution of the Hubbard model than the edge sites. In this paper, we systematically investigate results in the spirit of this center-focused scheme for several cluster sizes up to $8\times 8$ in and out of particle-hole symmetry. First we analyze the metal-insulator crossovers and transitions of the half-filled Hubbard model on a simple square lattice. We find that the critical interaction of the crossover is reduced with increasing cluster sizes and the critical temperature abruptly drops for the $4\times 4$ cluster. Second, for this cluster size, we apply the center-focused scheme to a system with more realistic tight-binding parameters, investigating its pseudogap regime as a function of temperature and doping, where we find doping dependent metal-insulator crossovers, Lifshitz transitions and a strongly renormalized Fermi-liquid regime. Additionally to diagnosing the real space origin of the suppressed antinodal spectral weight in the pseudogap regime, we can infer hints towards underlying charge ordering tendencies.Comment: 29 pages, 15 figure

Smog Nitrogen and the Rapid Acidification of Forest Soil, San Bernardino Mountains, Southern California

We report the rapid acidification of forest soils in the San Bernardino Mountains of southern California. After 30 years, soil to a depth of 25 cm has decreased from a pH (measured in 0.01 M CaCl2) of 4.8 to 3.1. At the 50-cm depth, it has changed from a pH of 4.8 to 4.2. We attribute this rapid change in soil reactivity to very high rates of anthropogenic atmospheric nitrogen (N) added to the soil surface (72 kg ha–1 year–1) from wet, dry, and fog deposition under a Mediterranean climate. Our research suggests that a soil textural discontinuity, related to a buried ancient landsurface, contributes to this rapid acidification by controlling the spatial and temporal movement of precipitation into the landsurface. As a result, the depth to which dissolved anthropogenic N as nitrate (NO3) is leached early in the winter wet season is limited to within the top ~130 cm of soil where it accumulates and increases soil acidity

Annual and monthly runoff analysis in the Elqui River, Chile, a semi-arid snow-glacier fed basin

Balocchi, F., Pizarro, R., Meixner, T., & Urbina, F. (November-   December, 2017). Annual and monthly runoff analysis in   the Elqui River, Chile, a semi-arid snow-glacier fed basin.   Water Technology and Sciences (in Spanish), 8(6), 23-35, DOI:   10.24850/j-tyca-2017-06-02.   Climate change and its relationship to temperature are   critical factors affecting glaciers, especially when populations   depend on these ice reservoirs. The use of the precipitationrunoff   coefficient in semi-arid, mountainous regions that   are fed by glaciers can lead to important findings about   how glacial melt responds to climate change. This study   analyzed 40 years of monthly and annual precipitation   and runoff data (1970-2009) from four sub-basins of the   Elqui River (29° 27’- 30° 34’ S and 71° 22’- 69° 52’ W), in   the Coquimbo region of Chile. The Elqui basin has a rainsnow-   glacial melt regime. The areal average rainfall was   estimated using the Thiessen polygon method. Gumbel   and Goodrich probability distribution functions and the   Log-Normal Probability Density Function (PDF) were used   to understand the temporal behavior of precipitation and   streamflow. The data-time behavior and PP Q-1 coefficients   were also analyzed. And the Mann-Kendall (MK) test was   used to compare the results. No trends were found for flow,   while a negative trend in rainfall was identified. The summer   flows were notable, which remained constant. In spite of the   differences between the PP Q-1 coefficient and the MK test,   the flow clearly does not come from rainfall but rather from   glacial melt