Band gaps of crystalline solids from Wannier-localization–based optimal tuning of a screened range-separated hybrid functional

Accurate prediction of fundamental band gaps of crystalline solid-state systems entirely within density functional theory is a long-standing challenge. Here, we present a simple and inexpensive method that achieves this by means of nonempirical optimal tuning of the parameters of a screened range-separated hybrid functional. The tuning involves the enforcement of an ansatz that generalizes the ionization potential theorem to the removal of an electron from an occupied state described by a localized Wannier function in a modestly sized supercell calculation. The method is benchmarked against experiment for a set of systems ranging from narrow band-gap semiconductors to large band-gap insulators, spanning a range of fundamental band gaps from 0.2 to 14.2 electronvolts (eV), and is found to yield quantitative accuracy across the board, with a mean absolute error of ∼0.1 eV and a maximal error of ∼0.2 eV.

The Application of the Law of Occupation in Maritime Zones and Rights to ‘Occupied’ Marine Resources

This article seeks to contribute to the emerging literature concerning the application of belligerent occupation in maritime zones of the occupied State. It supports the approach that the law of occupation and the law of the sea apply simultaneously in case of occupation of coastal States, offering a new perspective on the jurisdiction of the occupying power to exploit marine resources in the occupied State’s continental shelf and exclusive economic zone. This perspective highlights some issues that have been ignored in the literature thus far to better understand the rights and obligations of the relevant Parties with respect to maritime zones of the occupied State.

Direct observation and manipulation of hot electrons at room temperature

In modern electronics and optoelectronics, hot electron behaviors are highly concerned since they determine the performance limit of a device or system, like the associated thermal or power constraint of chips, the Shockley-Queisser limit for solar cell efficiency. Up-to-date, however, the manipulation of hot electrons is mostly based on conceptual interpretations rather than a direct observation. The problem arises from a fundamental fact that energy-differential electrons are mixed up in real-space, making it hard to distinguish them from each other by standard measurements. Here we demonstrate a distinct approach to artificially (spatially) separate hot electrons from cold ones in semiconductor nanowire transistors, which thus offers a unique opportunity to observe and modulate electron occupied state, energy, mobility, and even its path. Such a process is accomplished through the scanning-photocurrent-microscopy (SPCM) measurements by activating the intervalley-scattering events and one-dimensional charge-neutrality rule. Findings discovered here may provide a new degree of freedom in manipulating nonequilibrium electrons for both electronic and optoelectronic applications.

Globus pallidus dynamics reveal covert strategies for behavioral inhibition

Flexible behavior requires restraint of actions that are no longer appropriate. This behavioral inhibition critically relies on frontal cortex - basal ganglia circuits. Within the basal ganglia, the globus pallidus pars externa (GPe) has been hypothesized to mediate selective proactive inhibition: being prepared to stop a specific action, if needed. Here we investigate population dynamics of rat GPe neurons during preparation-to-stop, stopping, and going. Rats selectively engaged proactive inhibition towards specific actions, as shown by slowed reaction times (RTs). Under proactive inhibition, GPe population activity occupied state-space locations farther from the trajectory followed during normal movement initiation. Furthermore, the state-space locations were predictive of distinct types of errors: failures-to-stop, failures-to-go, and incorrect choices. Slowed RTs on correct proactive trials reflected starting bias towards the alternative action, which was overcome before progressing towards action initiation. Our results demonstrate that rats can exert cognitive control via strategic adjustments to their GPe network state.

Cleanroom Fan Energy Reduction—Airflow Control Retrofit Based on Continuous, Real-time Particle Sensing

Cleanrooms are utilized in electronics, semiconductor, aerospace, pharmaceutical, automotive, optical, medical device, and food processing facilities where air cleanliness is required to prevent defects in high-tech or high-value products. Compared to general commercial space, cleanrooms typically use 5 to 50 times the energy for the same area. One key reason is the high volume of conditioned and filtered air required to make the room air cleaner, which is measured in room-average particle concentration. The technology in this study uses real-time continuous particle sensors as feedback signals to automatically adjust fan speed. The system can modulate fan speed and provide the correct amount of airflow into the cleanroom to prevent over-supply and save energy. In typical manufacturing cleanrooms, the unoccupied state (evenings and weekends) is approximately two times longer than the occupied state (operational work hours), and particle generation (from personnel, equipment, and process) is much lower during the unoccupied state. Limited components and parts are required to apply the technology in this study into the design of a new cleanroom or to integrate the technology into existing cleanroom fan systems.

The Effect of Point Defects on the Electronic Density of States of ScMN2-Type (M = V, Nb, Ta) Phases

ScMN2-type (M = V, Nb, Ta) phases are layered materials that have been experimentally reported for M = Ta and Nb. They are narrow-bandgap semiconductors with potentially interesting thermoelectric properties. Point defects such as dopants and vacancies largely affect these properties, motivating the need to investigate these effects. In particular, asymmetric peak features in the density of states (DOS) close to the highest occupied state is expected to increase the Seebeck coefficient. Here, we used first principles calculations to study the effects of one vacancy or one C, O, or F dopant on the DOS of the ScMN2 phases. We used density functional theory to calculate formation energy and the density of states when a point defect is introduced in the structures. In the DOS, asymmetric peak features close to the highest occupied state were found as a result of having a vacancy in all three phases. Furthermore, one C dopant in ScTaN2, ScNbN2, and ScVN2 implies a shift of the highest occupied state into the valence band, while one O or F dopant causes a shift of the highest occupied state into the conduction band.

Territorial Jurisdiction and Positive Obligations of an Occupied State

The international law of occupation—as it has developed since the nineteenth century—traditionally regulates the conduct and obligations of occupying forces. Very little is said about the obligations of an occupied State, or a ‘victim’ State. This chapter focuses on a limited practice of the European Court of Human Rights in developing some principles in this respect. The main emphasis is put on the landmark judgment Ilascu v Moldova and Russia, in which, for the first time, the Court has found that a State, which lost effective control over a part of its territory and was unable to exercise its jurisdiction there, still had some positive obligations deriving from its de jure jurisdiction. It is argued that the Court’s approach represented a new development in international law, which traditionally considered human rights obligations to be primarily triggered by an effective territorial control. It is further discussed that it might be quite difficult to reconcile positive obligations towards people remaining in occupied territories with a State’s obligation to refrain from supporting separatist regimes. Substitution of effective control for the concept of ‘positive obligations’ necessitates a very delicate assessment of different political, diplomatic, judicial, and other measures, which requires a high degree of sensitivity on the part of the international court. The scope of the positive obligations of an injured State vis-à-vis the positive obligations of an occupying State needs to be elucidated further.

Luminescent properties and first-principles calculations of (Cr,Ca):YAG crystals

The single crystals of YAG, Cr:YAG and (Cr,Ca):YAG were grown in an optical floating zone furnace. The experimental results show that the optical bandgap of the YAG, (Cr,Ca):YAG and Cr:YAG crystals is about 6.52, 6.31 and 5.50 eV, respectively. The optical bandgap of the (Cr,Ca):YAG crystal is smaller than YAG and larger than Cr:YAG. First-principles calculation results showed that the additions of Cr into YAG will give rise to the change of the electronic states. In a Cr:YAG crystal, the Cr[Formula: see text] impurity introduces a band of 3[Formula: see text] occupied state near the Fermi level, which significantly narrowed the bandgap of Cr:YAG. In a (Cr,Ca):YAG crystal, as the Ca[Formula: see text] ions substitute for the Y[Formula: see text] ions, some of the Cr[Formula: see text] ions will change into Cr[Formula: see text] ions due to the charge balance, which increased the bandgap of the (Cr,Ca):YAG crystal in comparison with that of the Cr:YAG crystal. The calculation is in agreement with the experimental results.