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Full-Text Articles in Physical Sciences and Mathematics

Optical Properties Of Antiferroelectric Cs2nb4o11: Absorption Spectra And First-Principles Calculations, H. L. Liu, C. R. Huang, G. F. Luo, Wai-Ning Mei Nov 2011

Optical Properties Of Antiferroelectric Cs2nb4o11: Absorption Spectra And First-Principles Calculations, H. L. Liu, C. R. Huang, G. F. Luo, Wai-Ning Mei

Chemistry Faculty Publications

We report a joint experimental and theoretical investigation of the optical properties of Cs2Nb4O11. In room temperature optical absorption spectra, we found a direct gap about 3.5560.05 eV and charge transfer excitations at about 4.96 and 6.08 eV, which are in good agreement with the first-principles calculations. Upon passing through the 165 C antiferroelectric to paraelectric phase transition, the peak energies of two charge transfer bands display almost no temperature dependence, yet they become even broader and exhibit enhanced oscillator strength. We infer this intriguing behavior as the manifestation of Nb cation distortions due to the charge-lattice interaction.


The Tyranny Of The Vital Few: The Pareto Principle In Language Design, Victor L. Winter, James L. Perry, Harvey Siy, Satish Srinivasan, Ben Farkas, James Mccoy Jan 2011

The Tyranny Of The Vital Few: The Pareto Principle In Language Design, Victor L. Winter, James L. Perry, Harvey Siy, Satish Srinivasan, Ben Farkas, James Mccoy

Chemistry Faculty Publications

Modern high-level programming languages often contain constructs whose semantics are non-trivial. In practice how- ever, software developers generally restrict the use of such constructs to settings in which their semantics is simple (programmers use language constructs in ways they understand and can reason about). As a result, when developing tools for analyzing and manipulating software, a disproportionate amount of effort ends up being spent developing capabilities needed to analyze constructs in settings that are infrequently used. This paper takes the position that such distinctions between theory and practice are an important measure o f the analyzability of a language.