Dynamic correlations in symmetric electron-electron and electron-hole bilayers

The ground-state behavior of the symmetric electron-electron and electron-hole bilayers is studied by including dynamic correlation effects within the quantum version of Singwi, Tosi, Land, and Sjolander (qSTLS) theory. The static pair-correlation functions, the local-field correction factors, and the ground-state energy are calculated over a wide range of carrier density and layer spacing. The possibility of a phase transition into a density-modulated ground state is also investigated. Results for both the electron-electron and electron-hole bilayers are compared with those of recent diffusion Monte Carlo (DMC) simulation studies. We find that the qSTLS results differ markedly from those of the conventional STLS approach and compare in the overall more favorably with the DMC predictions. An important result is that the qSTLS theory signals a phase transition from the liquid to the coupled Wigner crystal ground state, in both the electron-electron and electron-hole bilayers, below a critical density and in the close proximity of layers (d <~ r_sa_0^*), in qualitative agreement with the findings of the DMC simulations.Comment: 13 pages, 11 figures, 2 table

Excitonic condensation in a symmetric electron-hole bilayer

Using Diffusion Monte Carlo simulations we have investigated the ground state of a symmetric electron-hole bilayer and determined its phase diagram at T=0. We find clear evidence of an excitonic condensate, whose stability however is affected by in-layer electronic correlation. This stabilizes the electron-hole plasma at large values of the density or inter-layer distance, and the Wigner crystal at low density and large distance. We have also estimated pair correlation functions and low order density matrices, to give a microscopic characterization of correlations, as well as to try and estimate the condensate fraction.Comment: 4 pages, 3 figures, 2 table

Metal-insulator transition in disordered 2DEG including temperature effects

We calculate self-consistently the mutual dependence of electron correlations and electron-defect scattering for a two dimensional electron gas at finite temperature. We employ an STLS approach to calculate the electron correlations while the electron scattering rate off Coulombic impurities and surface roughness is calculated using self-consistent current-relaxation theory. The methods are combined and self-consistently solved. We discuss a metal-insulator transition for a range of disorder levels and electron densities. Our results are in good agreement with recent experimental observations.Comment: 4 pages, RevTeX + epsf, 5 figure

Fine structure in the off-resonance conductance of small Coulomb blockade systems

We show how a fine, multiple-peak structure can arise in the off-resonance, zero-bias conductance of Coulomb blockade systems. In order to understand how this effect comes about one must abandon the orthodox, mean-field understanding of the Coulomb blockade phenomenon and consider quantum fluctuations in the occupation of the single-particle electronic levels. We illustrate such an effect with a spinless Anderson-like model for multi-level systems and an equation-of-motion method for calculating Green's functions that combines two simple decoupling schemes.Comment: 5 pages, 3 figures, postscript file also available at http://www.pa.uky.edu/~palacios/papers/eom.ps One figure added. Discussion of results extende

STUDI KOMPARATIF EKONOMI SIRKULAR DALAM ARAH KEBIJAKAN HUKUM PENGELOLAAN SAMPAH KEMASAN PLASTIK DI INDONESIA DAN JERMAN

Pengelolaan sampah yang baik modern ini berpedoman pada konsep ekonomi sirkular, yaitu pengurangan serta pemanfaatan sampah melalui daur ulang ataupun pendayagunaan kembali sehingga membuat siklus tertutup. Maka dari itu dilakukan penelitian normatif untuk melihat perbandingan komparatif kebijakan hukum pengelolaan sampah Indonesia dan Jerman dalam perspektif penerapan konsep ekonomi sirkuler. Peneltian ini menemukan bahwa meskipun kebijakan hukum Indonesia dan Jerman mengarah serta mencerminkan konsep ekonomi sirkuler, pada realitanya pelaksanaannya tidak berhasil mencapai ekonomi sirkuler. Hal ini terlihat dari kendala ekonomi, fasilitas, dan pemahaman masyarakat, meskipun bank sampah berpotensi meningkatkan partisipasi masyarakat dan produsen dalam pengelolaan sampah di Indonesia. Selain itu di Jerman walaupun angka pengumpulan dan pendauran ulang sampah tinggi, akan tetapi ternyata tingkat daur ulang secara energi yang lebih tinggi membuat ekonomi sirkular belum benar-benar dapat tercapai. Oleh karena itu penerapan kebijakan pengelolaan sampah kemasan plastik harus diawasi dan diterapkan dengan tegas untuk jalannya sistem yang benar-benar efektif mengubah pola konsumsi industri dan masyarakat menjadi ekonomi sirkuler

Dynamic exchange-correlation potentials for the electron gas in dimensionality D=3 and D=2

Recent progress in the formulation of a fully dynamical local approximation to time-dependent Density Functional Theory appeals to the longitudinal and transverse components of the exchange and correlation kernel in the linear current-density response of the homogeneous fluid at long wavelength. Both components are evaluated for the electron gas in dimensionality D=3 and D=2 by an approximate decoupling in the equation of motion for the current density, which accounts for processes of excitation of two electron-hole pairs. Each pair is treated in the random phase approximation, but the role of exchange and correlation is also examined; in addition, final-state exchange processes are included phenomenologically so as to satisfy the exactly known high-frequency behaviours of the kernel. The transverse and longitudinal spectra involve the same decay channels and are similar in shape. A two-plasmon threshold in the spectrum for two-pair excitations in D=3 leads to a sharp minimum in the real part of the exchange and correlation kernel at twice the plasma frequency. In D=2 the same mechanism leads to a broad spectral peak and to a broad minimum in the real part of the kernel, as a consequence of the dispersion law of the plasmon vanishing at long wavelength. The numerical results have been fitted to simple analytic functions.Comment: 13 pages, 11 figures included. Accepted for publication in Phys. Rev.

Beyond the Individual in Controversial Science-Based Technology Attitude Formation and Regulation: The State Construction of Policy Alternatives in Asia

10.2139/ssrn.17175151-3

Improving green literacy and environmental culture associated with youth participation in circular economy: a case study of Vietnam

Circular economy (CE), a sustainability concept that promotes resource efficiency and waste reduction, has garnered significant popularity in recent years due to its potential to address pressing environmental and economic challenges. This study employs the Bayesian mindsponge framework (BMF) to explore what drives young adults’ pro-environmental behavior and purchases of green products at different levels of price. The results show that young adult’s knowledge of CE and care about environmental protection and energy saving encourages the practice of waste classification, while factors that affect their willingness to pay (WTP) more for green and energy-saving products vary at different price tiers