Xiaoli Wang

Beyond the Mg–O pathway, RE–H coupling stabilizes adsorption, weakens Mg–H bonds, and lowers the dehydrogenation barrier from 0.48 eV to 0.13 eV.

The manipulation of quantum states in triple-decker organometallic molecules remains challenging due to their complex many-body interactions. In this study, we combine density functional theory (DFT) and the hierarchical equations of motion (HEOM) to map, for the first time, the evolution of quantum states in a triple-decker dinuclear complex under mechanical manipulation by a magnetic cobalt tip. DFT calculations demonstrate that the tip approach induces substantial structural distortion of the molecular framework, which triggers a reconstruction of the internal magnetic coupling network. This process is accompanied by an evolution of the electronic structure that includes modifications to the local density of states, magnetic moment, spin-state populations, and molecular orbital hybridization characteristics. By solving the spin-polarized Anderson model using the HEOM method, we have revealed the dynamic evolution of strongly correlated Kondo effects. When the system enters the contact regime, the Kondo resonance peak exhibits asymmetric splitting, where the splitting characteristics exhibit a simultaneous dependence on the spin polarization degree of the electrodes and the coupling strength between the impurity and the electrodes. These atomic-scale insights into the external control of molecular quantum states provide a robust framework for the future design of molecular spintronic devices.

α-AlH₃ is regarded as one of the most promising hydrogen storage materials due to its high hydrogen storage capacity (10.1 wt.%, 148 kg·m⁻³). However, in practical applications, the associated hydrogen release temperature remains relatively high. To effectively address this issue, hollow structured Fe@C nanorods derived from Fe-MOF are introduced as highly efficient catalyst to optimize the dehydrogenation properties of α-AlH₃. Comparatively, the initial hydrogen release temperature of α-AlH₃ + 3 wt.% Fe@C is reduced to 94.2 °C, which is significantly lower than that of pure α-AlH₃ (137.8 °C). At 100 and 120 °C, it exhibits hydrogen capacities of 5.38 wt.% and 7.47 wt.%, respectively, whereas pure α-AlH₃ only delivers hydrogen capacities of 0.24 wt.% and 5.94 wt.% under the same temperatures. The density functional theory (DFT) calculations further indicate that the existence of Fe@C catalyst can make the length of Al–H bond increase, which is more conducive to the release of hydrogen. The results show that the synergistic effect of Fe and porous carbon in Fe@C nanorods can improve the hydrogen desorption kinetics of α-AlH₃, providing a good prospect for the application of α-AlH₃ in hydrogen storage fields.

The interactions between a magnetic tip and local spin impurities initiate unconventional Kondo phenomena, such as asymmetric suppression or even splitting of the Kondo peak. However, a lack of realistic theoretical models and comprehensive explanations for this phenomenon persists due to the complexity of the interactions. This research employs a joint method of density functional theory (DFT) and hierarchical equation of motion (HEOM) to simulate and contrast the modulation of the spin state and Kondo behavior in the Fe/Cu(100) system with two distinct magnetic tips. A cobalt tip, possessing a larger magnetic moment, incites greater atomic displacement of the iron atom, more notable alterations in electronic structure, and enhanced charge transfer with the environment compared with the control process utilizing a nickel tip. Furthermore, the Kondo resonance undergoes asymmetric splitting as a result of the ferromagnetic correlation between the iron atom and the magnetic tip. The Co tip's higher spin polarization results in a wider spacing between the splitting peaks. This investigation underscores the precision of the DFT + HEOM approach in predicting complex quantum phenomena and explaining the underlying physical principles. This provides valuable theoretical support for developing more sophisticated quantum regulation experiments.

Enhanced Multimedia Broadcast/Multicast Service (eMBMS) is a new function defined in 3GPP Release 8 specification, which supports download delivery and streaming delivery to group users in LTE mobile networks. For download delivery, there are two mechanisms implemented in different entities to improve reliability: (1) At eBMSC (Enhanced Broadcast/Multicast Service Center), Raptor code is implemented in software to provide packet-level protection in the application layer; (2) At eNB (Enhanced NodeB), HARQ is used to provide bit-level protection in the link-layer. In this paper, we first analyze the redundancy caused by the coexistence of HARQ and Raptor, and then propose a novel HARQ retransmission policy to reduce the redundancy. Simulation results, using the Matlab and OPNET, confirm significant improvement.