A direct diabatic states construction method with consistent orbitals for valence and Rydberg states.

This work presents a novel methodology termed Direct Diabatic States Construction (DDSC), which integrates fragment wavefunctions into an anti-symmetric wavefunction for the entire system. Using fragment-localized state-consistent molecular orbitals, this approach enables direct construction of all diabatic states at the same root. Each diabatic state is formed as a linear combination of a set of diabatic configurations.

Unveiling the intermediate hydrated proton in water through vibrational analysis on the 1750 cm signature.

Hydration of proton is the key to understand the acid-base chemistry and biochemical processes, for which the Zundel and Eigen cations have been recognized as the foundation. However, their dominance remains contentious due to the challenge of attributing the infrared signature at  ~1750 cm, stemming from the theoretical dilemma of balancing structural diversity and solvent fluctuations. Herein, we circumvent this obstacle by devising an integrated approach for computing frequency-specific vibrational vectors via inverse Fourier transform of the vibrational density of states.

An iterative and automatic collective variable optimization scheme via unsupervised feature selection with CUR matrix decomposition.

Phase transitions frequently involve surmounting significant energy barriers, necessitating the construction of collective variables (CVs) to facilitate enhanced sampling of high-energy structures in molecular dynamics simulations. However, optimizing CVs remains a formidable challenge, particularly when limited prior knowledge about the transition process is available. This study presents an unsupervised approach for optimizing the CVs by iteratively applying the principal component analysis algorithm on the representative feature variables generated with the CUR method (an efficient feature space contraction algorithm that can be employed to seek the representative feature variables).

Kylin-V: An open-source package calculating the dynamic and spectroscopic properties of large systems.

Quantum dynamics simulation and computational spectroscopy serve as indispensable tools for the theoretical understanding of various fundamental physical and chemical processes, ranging from charge transfer to photochemical reactions. When simulating realistic systems, the primary challenge stems from the overwhelming number of degrees of freedom and the pronounced many-body correlations. Here, we present Kylin-V, an innovative quantum dynamics package designed for accurate and efficient simulations of dynamics and spectroscopic properties of vibronic Hamiltonians for molecular systems and their aggregates.

Synergistic Al-Al Dual-Atomic Site for Efficient Artificial Nitrogen Fixation.

Synthesis of ammonia by electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the Haber-Bosch process. However, it is commonly obstructed by the high activation energy. Here, we report the design and synthesis of an Al-Al bonded dual atomic catalyst stabilized within an amorphous nitrogen-doped porous carbon matrix (AlNC) with high NRR performance.

Spin-Adapted Externally Contracted Multireference Configuration Interaction Method Based on Selected Reference Configurations.

As one kind of approximation of the full configuration interaction solution, the selected configuration interaction (sCI) methods have been shown to be valuable for large active spaces. However, the inclusion of dynamic correlation beyond large active spaces is necessary for more quantitative results. Since the sCI wave function can provide a compact reference for multireference methods, previously, we proposed an externally contracted multireference configuration interaction method using the sCI reference reconstructed from the density matrix renormalization group wave function [ 4747-4755].

Mechanistic Insights into Water Autoionization through Metadynamics Simulation Enhanced by Machine Learning.

Characterizing the free energy landscape of water ionization has been a great challenge due to the limitations from expensive ab initio calculations and strong rare-event features. Lacking equilibrium sampling of the ionization pathway will cause ambiguities in the mechanistic study. Here, we obtain convergent free energy surfaces through nanosecond timescale metadynamics simulations with classical nuclei enhanced by atomic neural network potentials, which yields good reproduction of the equilibrium constant (pK_{w}=14.

Visualization of Electron Density Changes Along Chemical Reaction Pathways.

We propose a simple procedure for visualizing the electron density changes (EDC) during a chemical reaction, which is based on a mapping of rectangular grid points for a stationary structure into (distorted) positions around atoms of another stationary structure. Specifically, during a small step along the minimum energy pathway (MEP), the displacement of each grid point is obtained as a linear combination of the motion of all atoms, with the contribution from each atom scaled by the corresponding Hirshfeld weight. For several reactions (identity S2, Claisen rearrangement, Diels-Alder reaction, [3+2] cycloaddition, and phenylethyl mercaptan attack on pericosine A), our EDC plots showed an expected reduction of electron densities around severed bonds (or those with the bond-order lowered), with the opposite observed for newly-formed or enhanced chemical bonds.

Benzo[]quinoxaline-Based Complexes [Ir(pbt)(dppn)]Cl and [Ir(pt)(dppn)]Cl: Modulation of Photo-Oxidation Activity and Light-Controlled Luminescence.

Based on benzo[]dipyrido[3,2-a:2',3'-]phenazine (dppn) with photo-oxidation activity, complexes [Ir(pbt)(dppn)]Cl () and [Ir(pt)(dppn)]Cl () have been synthesized (pbtH = 2-phenylbenzothiazole, and ptH = 2-phenylthiazole), with two aims, including studying the influence of the cyclometalating ligands (pbt in , pt in ) on the photo-oxidation activity of these complexes and exploring their photo-oxidation-induced luminescence. Both H nuclear magnetic resonance (NMR) and electrospray (ES) mass spectrometry indicate that the benzo[]quinoxaline moiety in complex can be oxidized at room temperature upon irradiation with 415 nm light. Thus, this complex in CHCl shows photo-oxidation-induced turn-on yellow luminescence.

Hierarchical Mapping for Efficient Simulation of Strong System-Environment Interactions.

Quantum dynamics (QD) simulation is a powerful tool for interpreting ultrafast spectroscopy experiments and unraveling their microscopic mechanism in out-of-equilibrium excited state behaviors in various chemical, biological, and material systems. Although state-of-the-art numerical QD approaches such as the time-dependent density matrix renormalization group (TD-DMRG) already greatly extended the solvable system size of general linearly coupled exciton-phonon models with up to a few hundred phonon modes, the accurate simulation of larger system sizes or strong system-environment interactions is still computationally highly challenging. Based on quantum information theory (QIT), in this work, we realize that only a small number of effective phonon modes couple to the excitonic system directly regardless of a large or even infinite number of modes in the condensed phase environment.

The Existence of Periodic Solutions for Second-Order Delay Differential Systems.

In this paper, we consider a kind of second-order delay differential system. By taking some transforms, the property of delay is reflected in the boundary condition. The wonder is that the corrseponding first-order system is exactly the so-called -boundary value problem of Hamiltonian system which has been studied deeply by many mathematicians, including the authors of this paper.

Free-Standing Single Ag Nanowires for Multifunctional Optical Probes.

Miniaturized and manipulable optical probes are the foundation for developing in situ characterization devices in confined space. We developed two methods for fabricating free-standing single Ag nanowires (AgNWs) directly at the tip of a glass capillary either by chemical or electrochemical reduction. The electrochemical nature of both methods resulted in a rapid growth rate of AgNWs up to 1.

Controlled Fluorescence Enhancement of DNA-Binding Dye Through Chain Length Match between Oligoguanine and TOTO.

Fluorescent DNA-binding dyes are extensively employed as probe and biosensing in biological detection and imaging. Experiments and theoretical calculations of thiazole orange homodimeric (TOTO) dye binding to a single-strand DNA (ssDNA), poly(dG) ( = 2, 4, 6, 8), reveal that the = 6 complex shows about 300-fold stronger fluorescence than = 2, 4 and a slightly stronger one than = 8 complexes, which is benefited from the length match between TOTO and poly(dG). The machine learning, based on molecular dynamics trajectories, indicates that TOTO is featured by the dihedral angle along its backbone and its end-to-end distance, in which the latter one defines the stretch and hairpin structures of TOTO, respectively.

Importance of Au nanostructures in CO electrochemical reduction reaction.

Electrochemical conversion of CO into fuels is a promising means to solve greenhouse effect and recycle chemical energy. However, the CO reduction reaction (CORR) is limited by the high overpotential, slow kinetics and the accompanied side reaction of hydrogen evolution reaction. Au nanocatalysts exhibit high activity and selectivity toward the reduction of CO into CO.

Enhancing the Understanding of Hydrogen Evolution and Oxidation Reactions on Pt(111) through Ab Initio Simulation of Electrode/Electrolyte Kinetics.

The hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) play an important role in hydrogen-based energy conversion. However, the sluggish kinetics in alkaline media has raised debates on the relevant mechanism, especially on the role of surface hydroxyl (OH*). With the potential-related free energy profiles obtained with density functional theory calculations, the full pH range transient kinetics simulation of HER/HOR polarization curves on Pt(111) agrees well with experimental observations.

Time-dependent density matrix renormalization group quantum dynamics for realistic chemical systems.

Electronic and/or vibronic coherence has been found by recent ultrafast spectroscopy experiments in many chemical, biological, and material systems. This indicates that there are strong and complicated interactions between electronic states and vibration modes in realistic chemical systems. Therefore, simulations of quantum dynamics with a large number of electronic and vibrational degrees of freedom are highly desirable.

Exciton-Phonon Interaction Model for Singlet Fission in Prototypical Molecular Crystals.

In singlet fission (SF), a spin-conserving splitting of one singlet exciton into two triplet excitation states, the transition between localized electronic states can be controlled and modulated by delocalized lattice phonons. In this work, we built an exciton-phonon (ex-ph) interaction model accounting local electronic states coupled with both local molecular vibrations and low frequency intermolecular phonon modes for SF in crystalline tetracene and rubrene. On the basis of the calculated electronic couplings at the equilibrium structure of the molecular dimer, a superexchange path for SF was found for tetracene while couplings between the triplet pair (TT) state and other diabatic states are zero for rubrene due to the high symmetry.

Modifying decellularized aortic valve scaffolds with stromal cell-derived factor-1α loaded proteolytically degradable hydrogel for recellularization and remodeling.

Decellularized matrix is of great interest as a scaffold for the tissue engineering heart valves due to its naturally three-dimensional structure and bioactive composition. A primary challenge of tissue engineered heart valves based on decellularized matrix is to grow a physiologically appropriate cell population within the leaflet tissue. In this study, a composite scaffold was fabricated by the combination of a porous matrix metalloproteinase (MMP) degradable poly (ethylene glycol) (PEG) hydrogel that were loaded with stromal cell-derived factor-1α (SDF-1α) and a mechanically supportive decellularized porcine aortic valve.

How intermolecular interactions influence electronic absorption spectra: insights from the molecular packing of uracil in condensed phases.

The photoexcitation mechanism in photochemistry and photophysics is a key to understanding the photostability and photoreaction of nucleobases. Using a combination of the generalized energy-based fragmentation (GEBF) and quantum mechanical and molecular mechanical (GEBF-QM/MM) approach and the QM/MM approach, we have investigated the electronic absorption spectra for the π-π* transition of uracil in aqueous solution, amorphous solid, and crystal. Our results indicate that the intermolecular interactions in terms of molecular packing are crucial for the investigation of the absorption spectra of uracil in different environments.

An Elastic Autonomous Self-Healing Capacitive Sensor Based on a Dynamic Dual Crosslinked Chemical System.

Adopting self-healing, robust, and stretchable materials is a promising method to enable next-generation wearable electronic devices, touch screens, and soft robotics. Both elasticity and self-healing are important qualities for substrate materials as they comprise the majority of device components. However, most autonomous self-healing materials reported to date have poor elastic properties, i.

Origin of the overpotentials for HCOO and CO formation in the electroreduction of CO on Cu(211): the reductive desorption processes decide.

Electroreduction of CO on Cu surface provides the potential in producing hydrocarbons and other multi-carbon products. However, a comprehensive understanding of the potential-related mechanism is required to improve the product selectivity as well as to reduce the overpotentials. Herein, we systematically characterize the potential effect on the complete reaction pathways to CO and HCOO on the Cu(211) surface.

Efficient Reconstruction of CAS-CI-Type Wave Functions for a DMRG State Using Quantum Information Theory and a Genetic Algorithm.

We improve the methodology to construct a complete active space-configuration interaction (CAS-CI) expansion for density-matrix renormalization group (DMRG) wave functions using a matrix-product state representation, inspired by the sampling-reconstructed CAS [SR-CAS; Boguslawski , K. ; J. Chem.

Electronic Structures of Anti-Ferromagnetic Tetraradicals: Ab Initio and Semi-Empirical Studies.

The energy relationships and electronic structures of the lowest-lying spin states in several anti-ferromagnetic tetraradical model systems are studied with high-level ab initio and semi-empirical methods. The Full-CI method (FCI), the complete active space second-order perturbation theory (CASPT2), and the n-electron valence state perturbation theory (NEVPT2) are employed to obtain reference results. By comparing the energy relationships predicted from the Heisenberg and Hubbard models with ab initio benchmarks, the accuracy of the widely used Heisenberg model for anti-ferromagnetic spin-coupling in low-spin polyradicals is cautiously tested in this work.

Photoisomerization of silyl-substituted cyclobutadiene induced by σ → π* excitation: a computational study.

Photoinduced chemical processes upon Franck-Condon (FC) excitation in tetrakis(trimethylsilyl)-cyclobutadiene (TMS-CBD) have been investigated through the exploration of potential energy surface crossings among several low-lying excited states using the complete active space self-consistent field (CASSCF) method. Vertical excitation energies are also computed with the equation-of-motion coupled-cluster model with single and double excitations (EOM-CCSD) as well as the multireference Møller-Plesset (MRMP) methods. Upon finding an excellent coincidence between the computational results and experimental observations, it is suggested that the Franck-Condon excited state does not correspond to the first π-π* single excitation state (S1, 1(1)B1 state in terms of D2 symmetry), but to the second (1)B1 state (S3), which is characterized as a σ-π* single excitation state.