Tackling the Long-Standing Energy Gap Problem in Kohn-Sham Density Functional Theory

Jeng-Da Chai Associate Professor / Department of Physics Tackling the Long-Standing Energy Gap Problem in Kohn-Sham Density Functional Theory Over the past two decades, Kohn-Sham density functional theory (KS-DFT) has been one of the most popular theoretical methods for the study of the ground-state properties of large electronic systems. Although the essential ingredient of KS-DFT, the exact exchange-correlation (XC) energy functional Exc[r], has not been known, functionals based on the local density approximation (LDA) and generalized gradient approximations (GGAs), are reasonably accurate for properties governed by short-range XC effects, and…

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Effects of size diversity on trophic interactions in ocean ecosystems

Chih-hao Hsieh Associate Professor / Institute of Oceanography Effects of size diversity on trophic interactions in ocean ecosystems Lin Ye and Chih-hao Hsieh Institute of Oceanography, National Taiwan University With the aid of new technologies to measure zooplankton size and community structure, a group of scientists of National Taiwan University formulated a novel hypothesis: increasing predator size diversity enhances the strength of top-down control on prey through diet niche partitioning, and this hypothesis was supported by empirical plankton data in the East China Sea. This work is led by the…

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Scientist of National Taiwan University joining with an international team develops a new method that helps examine climate impacts on fisheries.

Chih-hao Hsieh Associate Professor / Institute of Oceanography Associate Professor, Chih-hao Hsieh, from the Institute of Oceanography/Institute of Ecology and Evolutionary Biology, together with an international research team develops a method that helps examine nonlinear climate impacts on Pacific sardines.  This study, published in Proceedings of the National Academy of Sciences (4/17/2013), provides a new solution to forecast how fishing, climate changes, and ecosystem condition can work in concert to affect the abundance of fish stock. In the early 1940s, California fishermen caught a great amount of sardine at a…

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Detecting Causality in Complex Ecosystems

Chih-hao Hsieh Associate Professor / Institute of Oceanography Scientist of National Taiwan University joining with an international team develops a new statistical method that can effectively investigate causal relationships in complex ecosystems. Associate Professor, Chih-hao Hsieh, from the Institute of Oceanography/Institute of Ecology and Evolutionary Biology, together with an international research team develops a method to examine causal relationships in nonlinear dynamic systems. This study, published in Science (10/26/2012), provides a potential solution to determine the causes driving changes in complex networks such as ecosystems. This method helps ecologists distinguish…

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Higgs transition from a magnetic Coulomb liquid to a ferromagnet in Yb2Ti2O7

Kao, Ying-Jer Associate Professor / Department of Physics Higgs transition from a magnetic Coulomb liquid to a ferromagnet in Yb2Ti2O7 Lieh-Jeng Chang , Shigeki Onoda, Yixi Su, Ying-Jer Kao , Ku-Ding Tsuei , Yukio Yasui, Kazuhisa Kakurai & Martin Richard Lees Nature Communications, 3, 992 (2012), (DOI: 10.1038/ncomms1989) Magnetic monopoles can be regarded as the magnetic version of a charged particle like electrons and protons. They carry an isolated magnetic pole, either the North or the South poles. Normally magnets come in the form of dipoles, with both North and…

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