Obtaining a material that can self-heal under ambient conditions is a great promise and challenge in smart materials science. This can be achieved by a special class of bonds called dynamic bonds. From these, diarylbibenzofuranone (DABBF) dynamic covalent bond is an appealing solution, but it cannot react with oxygen or it will not show self-healing behavior. On page 2675, G.R. Schleder, J.T. Arantes and A. Fazzio study the DABBF bond formation against oxidation using density functional theory (DFT). The cover image shows DABBF, oxygen, arylbenzofuranone (ABF), and its frontier orbitals. (DOI: 10.1002/jcc.24899)

Parallel Cascade Selection Molecular Dynamics (PaCS-MD) is an enhanced conformational sampling method for searching structural transition pathways from a given reactant to a product. In the present study, Temperature-Shuffled PaCS-MD (TSF-PaCS-MD) is proposed as a further extension of PaCS-MD in which the temperatures are shuffled among different replicas at the beginning of each cycle of conformational resampling. Through evaluations, it was confirmed that TSF-PaCS-MD remarkably accelerated structural transitions of proteins than the original PaCS-MD.

Obtaining a material that can self-heal under ambient conditions is a great promise and challenge in smart materials science. This can be achieved by a special class of bonds called dynamic bonds. From these, diarylbibenzofuranone (DABBF) dynamic covalent bond is an appealing solution, but it cannot react with oxygen or it will not show self-healing behavior. Here, using density functional theory, we study the DABBF bond formation against oxidation.

Intramolecular proton transfer (PT) process on thymine nucleobase between N3 and O2 atoms is explored in presence of hexacoordinated divalent metals cations Mg²⁺, Zn²⁺, and Hg²⁺. This PT proceeds as a two stages process. The first step involves the PT from one of the aqua ligands toward O2. The second stage is connected with the N3-proton abstraction. In the presence of the hexaaqua-cations, the activation barrier is at most 8 kcal/mol.

Samarium diiodide mediated reductive couplings of N-oxoalkyl-substituted methyl indole-3-carboxylates lead to benzannulated pyrrolizidines and indolizidines with a surprisingly high diastereoselectivity. Gibbs energies of reaction steps are calculated with dispersion corrected DFT and the solvation model D-COSMO-RS. In contrast to previous mechanistic proposals, the diastereoselectivity in the cyclization is found to be due to the formation of an energetically highly favorable chelate complex in which the final relative configuration is already preformed.

Challenging spin systems can often have multireference character that requires computationally intensive methods and significant decisions by a user to achieve accurate results. We investigate if Monte Carlo configuration interaction and the density matrix renormalization group can be applied in an approach that moves towards a “black box” implementation. We generally find qualitative agreement for the ordering of spin states for the systems considered.

Four pseudorandom number generators were compared with a physical, quantum-based random number generator using the NIST suite of statistical tests. We then measured the effect of the five random number generators on various calculated properties in different Markov-chain Monte Carlo simulations. The results show that poor quality pseudorandom number generators produce results that deviate significantly from those obtained with the quantum-based random number generator. In contrast, the Mersenne Twister pseudorandom generator and a 64-bit Linear Congruential Generator with a scrambler produce results that are statistically indistinguishable from those obtained with the quantum-based random number generator.

Four pseudorandom number generators were compared with a physical, quantum-based random number generator using the NIST suite of statistical tests. We then measured the effect of the five random number generators on various calculated properties in different Markov-chain Monte Carlo simulations. The results show that poor quality pseudorandom number generators produce results that deviate significantly from those obtained with the quantum-based random number generator. In contrast, the Mersenne-Twister pseudorandom generator and a 64-bit Linear Congruential Generator with a scrambler produce results that are statistically indistinguishable from those obtained with the quantum-based random number generator.

Illustration of the difference between restrained temperature multiplexed replica exchange molecular dynamics (MREMD, top) and restrained Hamiltonian multiplexed replica exchange molecular dynamics (HREMD, bottom). Exchange of temperatures only (MREMD) can result in getting trapped in topological mirror image structures (top right), while adding exchanges of the restraint weights (HREMD) enables the system to escape from such structures, owing to the weakening or removing restraints in a part of a trajectory (bottom right).