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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)

   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. Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn 2 O 4

   https://doi.org/10.1002/admi.201801923  

   Bassett, Kimberly L. ; Warburton, Robert E. ; Deshpande, Siddharth ; Fister, Timothy T. ; Ta, Kim ; Esbenshade, Jennifer L. ; Kinaci, Alper ; Chan, Maria K. Y. ; Wiaderek, Kamila M. ; Chapman, Karena W. ; et al ( January 2019 , Advanced Materials Interfaces)

   The deposition of protective coatings on the spinel LiMn₂O₄(LMO) lithium‐ion battery cathode is effective in reducing Mn dissolution from the electrode surface. Although protective coatings positively affect LMO cycle life, much remains to be understood regarding the interface formed between these coatings and LMO. Using operando powder X‐ray diffraction with Rietveld refinement, it is shown that, in comparison to bare LMO, the lattice parameter of a model Au‐coated LMO cathode is significantly reduced upon relithiation. Less charge passes through Au‐coated LMO in comparison to bare LMO, suggesting that the reduced lattice parameter is associated with decreased Li⁺solubility in the Au‐coated LMO. Density functional theory calculations show that a more Li⁺‐deficient near‐surface is thermodynamically favorable in the presence of the Au coating, which may further stabilize these cathodes through suppressing formation of the Jahn–Teller distorted Li₂Mn₂O₄phase at the surface. Electronic structure and chemical bonding analyses show enhanced hybridization between Au and LMO for delithiated surfaces leading to partial oxidation of Au upon delithiation. This study suggests that, in addition to transition metal dissolution from electrode surfaces, protective coating design must also balance potential energy effects induced by charge transfer at the electrode‐coating interface.

    

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3. Molybdenum Carbide Electrocatalyst In Situ Embedded in Porous Nitrogen‐Rich Carbon Nanotubes Promotes Rapid Kinetics in Sodium‐Metal–Sulfur Batteries

   https://doi.org/10.1002/adma.202106572  

   Hao, Hongchang ; Wang, Yixian ; Katyal, Naman ; Yang, Guang ; Dong, Hui ; Liu, Pengcheng ; Hwang, Sooyeon ; Mantha, Jagannath ; Henkelman, Graeme ; Xu, Yixin ; et al ( May 2022 , Advanced Materials)

   This is the first report of molybdenum carbide‐based electrocatalyst for sulfur‐based sodium‐metal batteries. MoC/Mo₂C is in situ grown on nitrogen‐doped carbon nanotubes in parallel with formation of extensive nanoporosity. Sulfur impregnation (50 wt% S) results in unique triphasic architecture termed molybdenum carbide–porous carbon nanotubes host (MoC/Mo₂C@PCNT–S). Quasi‐solid‐state phase transformation to Na₂S is promoted in carbonate electrolyte, with in situ time‐resolved Raman, X‐ray photoelectron spectroscopy, and optical analyses demonstrating minimal soluble polysulfides. MoC/Mo₂C@PCNT–S cathodes deliver among the most promising rate performance characteristics in the literature, achieving 987 mAh g⁻¹at 1 A g⁻¹, 818 mAh g⁻¹at 3 A g⁻¹, and 621 mAh g⁻¹at 5 A g⁻¹. The cells deliver superior cycling stability, retaining 650 mAh g⁻¹after 1000 cycles at 1.5 A g⁻¹, corresponding to 0.028% capacity decay per cycle. High mass loading cathodes (64 wt% S, 12.7 mg cm⁻²) also show cycling stability. Density functional theory demonstrates that formation energy of Na₂S_x(1 ≤x ≤ 4) on surface of MoC/Mo₂C is significantly lowered compared to analogous redox in liquid. Strong binding of Na₂S_x(1 ≤x ≤ 4) on MoC/Mo₂C surfaces results from charge transfer between the sulfur and Mo sites on carbides’ surface.

    

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4. 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)

   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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5. Charge Transport through Self‐Assembled Monolayers of Monoterpenoids

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

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

   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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