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  1. We have designed a [Fe(SH)4H]− model with the fifth proton binding either to Fe or S. We show that the energy difference between these two isomers (∆E) is hard to estimate with quantum-mechanical (QM) methods. For example, different density functional theory (DFT) methods give ∆E estimates that vary by almost 140 kJ/mol, mainly depending on the amount of exact Hartree–Fock included (0%–54%). The model is so small that it can be treated by many high-level QM methods, including coupled-cluster (CC) and multiconfigurational perturbation theory approaches. With extrapolated CC series (up to fully connected coupled-cluster calculations with singles, doubles, and triples) and semistochastic heat-bath configuration interaction methods, we obtain results that seem to be converged to full configuration interaction results within 5 kJ/mol. Our best result for ∆E is 101 kJ/mol. With this reference, we show that M06 and B3LYP-D3 give the best results among 35 DFT methods tested for this system. Brueckner doubles coupled cluster with perturbaitve triples seems to be the most accurate coupled-cluster approach with approximate triples. CCSD(T) with Kohn–Sham orbitals gives results within 4–11 kJ/mol of the extrapolated CC results, depending on the DFT method. Single-reference CC calculations seem to be reasonably accurate (giving an error of ∼5 kJ/mol compared to multireference methods), even if the D1 diagnostic is quite high (0.25) for one of the two isomers.

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    Free, publicly-accessible full text available July 28, 2024
  2. This work introduces an emerging application of aerosol sensors integrated inside electronic cigarettes. Using the aerosol sensors, particle size distribution, aerosol temperature, and target chemicals of the generated aerosols are measured before the aerosol is inhaled by a user. When a hazardous aerosol is detected, the user will be warned immediately to stop vaping. With extensive sensor data collected from every puff, an electronic cigarette becomes a smart mobile device, capable of tracking and improving a user's vaping habits. Experimental results on a prototype are presented and have shown great promises towards minimizing the health risks of vaping. 
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  3. Free, publicly-accessible full text available February 1, 2024
  4. Metachronal motions are ubiquitous in terrestrial and aquatic organisms and have attracted substantial attention in engineering for their potential applications. Hard‐magnetic soft materials are shown to provide new opportunities for metachronal wave‐modulated robotic locomotion by multi‐agent active morphing in response to external magnetic fields. However, the design and optimization of such magnetic soft robots can be complex, and the fabrication and magnetization processes are often delicate and time‐consuming. Herein, a computational model is developed that integrates granular models into a magnetic–lattice model, both of which are implemented in the highly efficient parallel computing platform large‐scale atomic/molecular massively parallel simulator (LAMMPS). The simulations accurately reproduce the deformation of single cilium, the metachronal wave motion of multiple cilia, and the crawling and rolling locomotion of magnetic cilia soft robots. Furthermore, the simulations provide insight into the spatial and temporal variation of friction forces and trajectories of cilia tips. The results contribute to the understanding of metachronal wave‐modulated locomotion and potential applications in the field of soft robotics and biomimetic engineering. The developed model also provides a versatile computational framework for simulating the movement of magnetic soft robots in realistic environments and has the potential to guide the design, optimization, and customization of these systems.

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  5. Free, publicly-accessible full text available March 30, 2024
  6. null (Ed.)
    Thickness-dependent reliability in 3D-Cap HfO2-based FeRAM capacitors has been studied. Results show endurance larger than 1011 cycles and >10 years of extrapolated retention time. A significant polarization gain was made possible due to trenched capacitors that enhanced the effective areas. A major cause of the endurance failure is the dielectric breakdown after numerous cycles, which is linked to the gate leakage currents. Our temperature-dependent study of I-V characteristics has revealed Fowler-Nordheim tunneling at low temperatures and Frenkel-Poole conduction at room-to-high temperatures as the culprits. Such findings will be helpful for future commercialization of this technology. 
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  7. Naeemi, A.J. (Ed.)
    Apparent ‘Negative Capacitance’ (NC) effects have been observed in some ferroelectric-dielectric (FE-DE) bilayers by pulse measurements, and the associated results have been published that claim to be direct evidence to support the quasi-static ‘negative capacitance’ (QSNC) idea. However, the ‘NC’ effects only occur when sufficiently high voltage is applied, and even exist in stand-alone FE capacitors. These results contradict the QSNC theory, as it predicts that once stabilized (requires a DE layer), the FE remains in the ‘NC’ state regardless of the applied voltage. In this letter, by the use of Nucleation-Limited-Switching (NLS) model, we present our results obtained from simulation of pulse measurements on samples that are similar to the published ones. The simulation results indicate that reverse polarization switching occurs upon the falling edge of the pulses, which leads to the apparent hysteresis-free NC effect. This work provides an alternative interpretation of the experimental results without invoking the QSNC theory. 
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  8. Liu, M. (Ed.)
    This work presents the design and experimental demonstration of a novel dual-storage-portnonvolatile SRAM based on back-end-of-the-line processed Hf0.5Zr0.5O2-based metal-ferroelectric-metalcapacitors, which offers significant advantages over the conventional single-storage-port version withoutarea penalty, and paves the way for implementing our proposed selector-free 3D cross-point memory. 
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  9. null (Ed.)