As a member of the extended MA(2)Z(4) family, current research on MGa2S4 (M = Mg, Ca, Sr) primarily focused on its potential applications in energy conversion. In this work, the geometric structure, quantum capacitance (CQ), and charge storage capacity (Q) of MGa2S4 (M = Mg, Ca, Sr) were investigated based on density functional theory (DFT) method. The effects of S-vacancy, light-element doping (B, N, O, Al, Si, P) and transition-metal doping (Sc, Ti, V, Cr, Mn, Fe) on capacitance properties of MGa2S4 were also systematically examined. The results indicated that pristine MGa2S4 structures exhibited excellent CQ and Q under negative voltage, and SrGa2S4 possessed the largest CQ (395.94 mu F/cm & sup2;) at -0.6 V. Under negative bias, the introduction of S-vacancy increased the maximum CQ of MgGa2S4 and CaGa2S4 by 10.68-15.03 mu F/cm & sup2;. Light-element doping led to a further increase in the CQ, with N-doped SrGa2S4 achieving the most remarkable value of 527.85 mu F/cm & sup2;. Interestingly, transition-metal doping induced multiple peaks in the CQ-voltage profiles, especially under positive bias. Under positive bias, Ti-doped MGa2S4 exhibited the most significant CQ values (217.78-245.08 mu F/cm & sup2;). Overall, the findings of this study are expected to advance the development of high-capacitance electrodes based on MGa2S4 materials.
The effect of off-centre charge ions on the structural properties of a planar electric double layer is explored by Monte Carlo simulations in the canonical ensemble. The ions are assumed to be equi-sized rigid spheres, with the charges located away from the geometrical centre of the spheres, but never outside the spheres. Both the positive and negative charges are located at the same distance from their respective parent sphere centres. The ionic species are immersed in a continuous structureless solvent in the vicinity of a uniformly charged and non-polarisable planar electrode. For a temperature of 298.15 K and molar concentration of 1 mol/dm 3 , the electrode-ion singlet distribution functions, the mean electrostatic potential and the orientation profile of the ions are reported for 1:1 ion valencies. The influence of the off-centre charge on the distribution functions seems to be more significant when the charge is closer to the surface of the spheres; on the other hand, the average orientation of the counterions tends to be linear near the charged electrode. No sign of charge inversion in the electrolyte was detected in this work.
In this study, we propose an extended Global Area Search (GLAS) algorithm for the automatic exploration of multistep transitions without specifying reaction coordinates in advance. The key concept of the original GLAS method is to introduce repulsive interactions among walkers representing molecular structures and to promote their dispersion by increasing these interactions, thereby enabling the system to overcome activation barriers and identify surrounding equilibrium structures (EQs). The proposed method inherits this core concept while introducing two important improvements to the original GLAS framework: (1) iterative cycles of local optimisation and exploration of surrounding EQs to trace multistep transitions, and (2) precise regulation of the walkers' energies to guide the exploration toward elementary transitions with activation barriers below a specified target energy. We demonstrate the effectiveness of this algorithm by applying it to the conformational changes of alanine dipeptide and the Cope rearrangement of 3-methyl-1,5-hexadiene. Specifically, all conformers of alanine dipeptide were located in a single exploration run, and the multistep pathway of the Cope rearrangement was successfully elucidated. Furthermore, the walkers automatically explored the chemical space, selectively identifying elementary transitions with activation barriers below the target energy for each step. These results indicate that the extended GLAS algorithm can efficiently traverse complex potential energy surfaces involving specific activation barriers in a stepwise manner, providing a powerful and versatile tool for exploring molecular structural changes.
The interplay between pi-electron delocalisation and superalkali behaviour in Li-decorated pi-conjugated species offers a unique platform for tuning electronic properties. To explore this synergy, a systematic investigation of C6 + 4kLi6 + 2k (k = 0-7) was performed, encompassing species from C6Li6 to C34Li20. The optimised geometries exhibit planar-to-quasi-planar frameworks with consistent Li-C coordination (similar to 1.9 & Aring;), indicating uniform binding across the series. A steady decrease in vertical ionisation energy (VIE) from 4.48 eV (C6Li6) to 3.12 eV (C34Li20) confirms their pronounced superalkali nature. Electronic-structure analysis shows that Li-induced charge-transfer enhances delocalisation throughout the carbon framework. Aromaticity descriptors (HOMA, NICS, NICSzz, PDI, and PLR) further support this behaviour, indicating that Li substitution modulates but does not disrupt the underlying conjugation. The concurrent reduction in VIE and HOMO-LUMO gap reflects a balance between intrinsic electronic delocalisation and Li-induced charge-transfer. These findings establish Li-decorated polycyclic species as tunable superalkali systems, providing insight into the design of extended pi-conjugated superalkali systems.
The photoabsorption and photoionization spectra of molecular nitrogen, N2 , near the first ionisation threshold display numerous intense resonances that have not been satisfactorily assigned to date. Principal among these is a pair of broad resonances between 126,200 and 126,600 cm -1 commonly referred to as the "cathedral" bands. Here, we present new double-resonance photoionization spectra in this region recorded via the a '' 1 Sigma g+,v '=0 intermediate state as well as new high-resolution, vacuum-ultraviolet photoabsorption spectra of 14 N 2 , 14 N 15 N, and 15 N 2 to provide additional insight into the assignment of these features. Progress towards a fully consistent interpretation of the existing data on these bands is discussed, and a route towards a comprehensive description of the N2 absorption spectrum up to the B 2 Sigma u+ state of N 2+ is proposed.
