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1. Revisiting the N ( N  + 1)/2‐site s ‐type Gaussian charge model for permutationally invariant polynomial fitting of global molecular tensor surfaces

   https://doi.org/10.1002/qua.27102  

   Kudratov, Sophia A.; Kaledin, Martina; Kaledin, Alexey L. (February 2023, International Journal of Quantum Chemistry)

   Abstract The exact expressions for the dipole, quadrupole, and octupoles of a collection ofNpoint charges involve summations of corresponding tensors over theNsites weighted by their charge magnitudes. When the point charges are atoms (in a molecule) theN‐site formula is an approximation, and one must integrate over the electron density to recover the exact multipoles. In the present work we revisit theN(N + 1)/2‐site point charge density model of Hall (Chem. Phys. Lett.6, 501, 1973) for the purpose of fitting ab initio derived multipole moment hypersurfaces using permutationally invariant polynomials (PIP). We examine new approaches in PIP‐fitting procedures for the dipole, quadrupole, octupole moments, and polarizability tensor surfaces (DMS, QMS, OMS and PTS, respectively) for a non‐polar CCl₄and a polar CHCl₃and show that compared to the primitiveN‐site model theN(N + 1)/2‐site model appreciably improves the relative RMSE of the DMS and does much more substantially so, by an order of magnitude, for the corresponding ones of QMS and OMS. Training datasets are obtained by sampling potential energies up to 18 000 cm⁻¹above the global minima, generated by molecular dynamics simulations at the DFT B3LYP/aug‐cc‐pVDZ level of theory. 

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2. Enhanced Thomson and Unusual Nernst Coefficients in 1T‐ TiSe2 Due to Bipolar Transport and CDW Phase Transition

   https://doi.org/10.1002/eem2.12879  

   Akhanda, Md_Sabbir; Dharmasiri, Kusal_Sachithra; Das, Sree_Sourav; Louca, Despina; Zebarjadi, Mona (January 2025, ENERGY & ENVIRONMENTAL MATERIALS)

   Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid‐state cooling but their efficiency is hindered by material limitations. Alternative routes based on the Thomson and Nernst effects offer new possibilities. Here, we present a comprehensive investigation of the thermoelectric properties of 1T‐TiSe₂, focusing on these effects around the charge density wave transition (≈200 K). The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450 μV K⁻¹at 184 K, surpassing the Seebeck coefficient. Furthermore, 1T‐TiSe₂exhibits a remarkably broad temperature range (170–400 K) with a Thomson coefficient exceeding 190 μV K⁻¹, a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges. Additionally, the Nernst coefficient exhibits an unusual temperature dependence, increasing with temperature in the normal phase, which we attribute to bipolar conduction effects. The combination of solid–solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range. 

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3. Charge Transport through Self‐Assembled Monolayers of Monoterpenoids

   https://doi.org/10.1002/anie.201902997  

   Cafferty, Brian J.; Yuan, Li; Baghbanzadeh, Mostafa; Rappoport, Dmitrij; Beyzavi, M. Hassan; Whitesides, George M. (May 2019, Angewandte Chemie International Edition)

   Abstract The nature of the processes at the origin of life that selected specific classes of molecules for broad incorporation into cells is controversial. Among those classes selected were polyisoprenoids and their derivatives. This paper tests the hypothesis that polyisoprenoids were early contributors to membranes in part because they (or their derivatives) could facilitate charge transport by quantum tunneling. It measures charge transport across self‐assembled monolayers (SAMs) of carboxyl‐terminated monoterpenoids (O₂C(C₉HX)) and alkanoates (O₂C(C₇HX)) with different degrees of unsaturation, supported on silver (Ag^TS) bottom electrodes, with Ga₂O₃/EGaIn top electrodes. Measurements of current density of SAMs of linear length‐matched hydrocarbons—both saturated and unsaturated—show that completely unsaturated molecules transport charge faster than those that are completely saturated by approximately a factor of ten. This increase in relative rates of charge transport correlates with the number of carbon–carbon double bonds, but not with the extent of conjugation. These results suggest that polyisoprenoids—even fully unsaturated—are not sufficiently good tunneling conductors for their conductivity to have favored them as building blocks in the prebiotic world. 

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4. Rainfall partitioning varies across a forest age chronosequence in the southern A ppalachian M ountains

   https://doi.org/10.1002/eco.2081  

   Brantley, Steven_T; Miniat, Chelcy_F; Bolstad, Paul_V (February 2019, Ecohydrology)

   Abstract Evaporation of precipitation from plant surfaces, or interception, is a major component of the global water budget. Interception has been measured and/or modelled across a wide variety of forest types; however, most studies have focused on mature, second‐growth forests, and few studies have examined interception processes across forest age classes. We present data on two components of interception, total canopy interception (E_i) and litter interception—that is, O_i + O_ehorizon layers—(E_ff), across a forest age chronosequence, from 2 years since harvest to old growth. We used precipitation, throughfall, and stemflow collectors to measure total rainfall (P) and estimateE_i; and collected litter biomass and modelled litter wetting and drying to estimate evaporative loss from litter. CanopyE_i,Pminus throughfall, increased rapidly with forest age and then levelled off to a maximum of 21% ofPin an old‐growth site. Stemflow also varied across stands, with the highest stemflow (~8% ofP) observed in a 12‐year‐old stand with high stem density. ModelledE_ffwas 4–6% ofPand did not vary across sites. Total stand‐level interception losses (E_i + E_ff) were best predicted by stand age (R² = 0.77) rather than structural parameters such as basal area (R² = 0.49) or leaf area (R² < 0.01). Forest age appears to be an important driver of interception losses from forested mountain watersheds even when stand‐level structural variables are similar. These results will contribute to our understanding of water budgets across the broader matrix of forest ages that characterize the modern forest landscape. 

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5. Collision cross‐section analysis of self‐assembled metallomacrocycle isomers and isobars via ion mobility mass spectrometry

   https://doi.org/10.1002/rcm.8717  

   Endres, Kevin_J; Barthelmes, Kevin; Winter, Andreas; Antolovich, Robert; Schubert, Ulrich_S; Wesdemiotis, Chrys (February 2020, Rapid Communications in Mass Spectrometry)

   RationaleCoordinatively driven self‐assembly of transition metal ions and bidentate ligands gives rise to organometallic complexes that usually contain superimposed isobars, isomers, and conformers. In this study, the double dispersion ability of ion mobility mass spectrometry (IM‐MS) was used to provide a comprehensive structural characterization of the self‐assembled supramolecular complexes by their mass and charge, revealed by the MS event, and their shape and collision cross‐section (Ω), revealed by the IM event. MethodsSelf‐assembled complexes were synthesized by reacting a bis(terpyridine) ligand exhibiting a 60^odihedral angle between the two ligating terpyridine sites (T) with divalent Zn, Ni, Cd, or Fe. The products were isolated as (Metal²⁺[T])_n(PF₆)_2nsalts and analyzed using IM‐MS after electrospray ionization (ESI) which produced several charge states from eachn‐mer, depending on the number of PF₆ˉ anions lost upon ESI. Experimental Ω data, derived using IM‐MS, and computational Ω predictions were used to elucidate the size and architecture of the complexes. ResultsOnly macrocyclic dimers, trimers, and tetramers were observed with Cd²⁺, whereas Zn²⁺formed the same plus hexameric complexes. These two metals led to the simplest product distributions and no linear isomers. In sharp contrast, Ni²⁺and Fe²⁺formed all possible ring sizes from dimer to hexamer as well as various linear isomers. The experimental and theoretical Ω data indicated rather planar macrocyclic geometries for the dimers and trimers, twisted 3D architectures for the larger rings, and substantially larger sizes with spiral conformation for the linear congeners. Adding PF₆ˉ to the same complex was found to mainly cause size contraction due to new stabilizing anion–cation interactions. ConclusionsComplete structural identification could be accomplished using ESI‐IM‐MS. Our results affirm that self‐assembly with Cd²⁺and Zn²⁺proceeds through reversible equilibria that generate the thermodynamically most stable structures, encompassing exclusively macrocyclic architectures that readily accommodate the 60^oligand used. In contrast, complexation with Ni²⁺and Fe²⁺, which form stronger coordinative bonds, proceeds through kinetic control, leading to more complex mixtures and kinetically trapped less stable architectures, such as macrocyclic pentamers and linear isomers. 

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