The chiral-induced spin selectivity (CISS) effect refers to electron transport through chiral (often organic) molecules becoming spin-polarized, without external magnetic fields. While widely observed experimentally, a comprehensive theoretical understanding of the CISS effect remains to be developed. This review provides an accessible perspective on the effect and a summary of emerging CISS theories. We begin with fundamental concepts involving spin-orbit coupling, symmetries, and quantum transport. Then, we review key theoretical approaches, including scattering-based, tight-binding, vibration-assisted transport, strong-correlation, and chiral phonon models for CISS, while addressing crucial related aspects associated with hopping/tunneling mechanisms, angular momentum conservation, and experimental probes of CISS. Beyond molecular-scale processes, we explore CISS-related phenomena in solids, including the Rashba-Edelstein effect and electrical magnetochiral anisotropy. By bridging molecular and solid-state perspectives, we aim to lower the barrier of entry for theoretical researchers interested in this exciting topic.
Organic compounds are key components of atmospheric aerosols and often act as surfactants in cloud droplets and fine particles. While the interfacial behavior of individual species in binary systems is fairly well-understood, less is known about interactions between multiple surface-active organics. We use classical molecular dynamics simulations to examine how short-chain (C3) and long-chain (C8) organics coadsorb at the air-water interface. Despite differences in functional groups and surface activity, all mixtures form mixed monolayers, with chain organization driven primarily by lateral van der Waals interactions. Importantly, coadsorption leads to interfacial behaviors distinct from those observed in binary systems, particularly due to the influence of weakly interacting short-chain molecules. These results suggest that simple additive models may not accurately predict the complex interplay between hydrophobic and hydrophilic forces in multicomponent surfactant mixtures. This has implications for understanding aerosol and cloud climate interactions and the role of organic surface films in atmospheric processes.
Water's ability to form hydrogen bond networks underlies its unique properties. Microhydration, which is the binding of a few water molecules to solutes, can significantly alter both the hydrogen bond network compared to pure water and the solute's structure. Here, we highlight selected solute-water complexes that display notable internal dynamics and structural changes upon microhydration, studied using a tight combination of rotational spectroscopy and quantum-chemical calculations. We also demonstrate how nuclear quadrupole coupling effectively probes changes in the electronic environment during microhydration, offering insights into processes such as acid dissociation.
Nanoporous materials including zeolites, metal-organic frameworks, and covalent organic frameworks offer high tunability and surface area, making them ideally suited to address global challenges such as CO2 capture and conversion, utilization of renewable feedstocks, and air purification. Molecular modeling is essential to enable atomic-scale design for optimal performance. Chemical transformations in these materials include not only catalytic reactions, but also local or global structural rearrangements and are strongly dependent on extreme operating conditions typical for industrial processes. The performance of industrial catalysts is governed by complex reaction networks and multiscale phenomena like diffusion and reactions, spanning a broad range of timescales and length scales. Recent advances at the intersection of quantum mechanics, statistical physics, and machine learning have significantly improved our ability to model complex chemical transformations in industrial catalysts and nanoporous materials. Herein, we review current modeling strategies and highlight future directions for predictive, multiscale simulations of nanoporous catalysts under realistic conditions.
Understanding how electric fields interact with molecular spins is critical for advancing quantum technologies. This review focuses on spin-electric coupling (SEC) in paramagnetic molecules. We examine how electric fields affect spin-Hamiltonian parameters, highlighting experimental techniques to investigate this phenomenon, such as electric field-modulated electron paramagnetic resonance and spin echo under pulsed electric fields. Key mechanisms, including spin-orbit coupling and through-bond interactions, are discussed across various systems, from lanthanides to frustrated spin triangles and helical chains. We present here recent studies demonstrating that SEC can induce measurable shifts in magnetic resonance spectra, revealing new strategies for electric field-based spin control. These insights pave the way for enhanced spin-based data storage and quantum computation, emphasizing the importance of symmetry, polarizability, and molecular design in optimizing SEC effects.
Apart from benzene, aromatic compounds, crucial in biological and chemical processes, were conspicuously absent from the interstellar inventory before 2017, despite extensive searches. Since then, high-resolution laboratory rotational spectroscopic studies in combination with extremely high-sensitivity spectral line surveys have led to the discovery of numerous cyclic and aromatic molecules in the starless dark cloud TMC-1, a source previously thought unsuitable for such chemical complexity. Detections include polycyclic aromatic hydrocarbons (PAHs) and their cyano derivatives with as many as seven fused rings. Discrepancies of more than four orders of magnitude between observed and predicted abundances challenge established astrochemical models. The detection of benzonitrile in other molecular clouds further suggests that aromatic chemistry is common in space. New spectroscopic studies and analysis methods hold promise to refine models of PAH formation and better constrain PAH stabilities in the diffuse gas, thereby aiding in the identification of the carriers of the diffuse interstellar and unidentified infrared emission bands, and potentially reshaping our understanding of the chemical pathways that link interstellar organic molecules to the origins of terrestrial carbon.
Water is one of the most extensively studied molecular systems, yet its behavior across different phases, interfaces, and chemical environments continues to challenge existing models. Over the past decade, the development of data-driven many-body potential energy functions (PEFs) within the many-body energy (MB-nrg) formalism has enabled simulations of water and aqueous systems with unprecedented predictive power. Rooted in the many-body expansion and rigorously derived from "gold standard" electronic structure data, these PEFs bridge quantum chemistry and statistical mechanics within a unified framework. In this article, we review how the MB-pol PEF for water and the MB-nrg PEFs for hydrated halide and alkali metal ions have reshaped our understanding of aqueous properties across the gas, liquid, and solid phases, offering detailed insights into hydrogen bonding, spectroscopy, isotope effects, and phase stability. By connecting length scales and timescales while maintaining quantum-mechanical accuracy, the data-driven MB-nrg formalism provides a robust foundation for realistic molecular simulations and offers new opportunities for addressing long-standing questions in physical chemistry and beyond.
Density functional theory (DFT) is widely used to describe electronic structure in chemistry, physics, and materials science. Its accuracy is constrained by the exchange-correlation (XC) functional, which remains an approximation in all practical implementations. In contrast, wavefunction theory (WFT) offers a systematically improvable description of electron correlation, albeit at a higher computational cost. The complementary strengths of DFT and WFT have motivated efforts to connect the two. Historically, such connections have centered on total energies and electron densities, but recent advances have expanded these bridges to include XC potentials and energy densities. This review highlights strategies for translating quantities from WFT to DFT, with a focus on extracting XC potentials and energy densities from wavefunctions. Challenges in using finite basis sets, and potential solutions to this problem, are highlighted. These approaches offer insights into the structure of the exact XC functional and practical tools for developing next-generation approximations with improved accuracy and generalizability.
Many technological and environmental processes take place at mineral-water interfaces, which makes detailed knowledge of the structure and interactions at aqueous mineral interfaces essential to understand these processes. Since mineral surfaces could become charged upon contact with electrolyte solutions, the interfacial water structure and properties are also influenced by the interactions of water and ions in solution with this surface charge. A particularly promising strategy for the investigation of neutral and charged mineral-water interfaces is the combination of nonlinear optical spectroscopy with atomic force microscopy (AFM). Nonlinear optical spectroscopy provides insights into the water orientation and dynamics at the interface, while AFM can resolve the interfacial water density and forces. In this review, we discuss how nonlinear optical spectroscopy and AFM can be used to investigate mineral-water interfaces and advance our fundamental understanding of aqueous mineral interfaces.
Recent advances in experimental and theoretical physical chemistry have provided a path for a new technique for routine chiral analysis of small organic molecules. Chiral tag rotational spectroscopy uses chiral derivatization to convert the enantiomers of an analyte into spectroscopically distinct diastereomers. The derivatization is achieved by forming molecular complexes between the analyte and a small, chiral molecule-the tag-via noncovalent interactions. These chiral tag complexes are formed in the molecular beam expansion used to inject samples into Fourier transform microwave spectrometers. Rotational spectroscopy analysis, guided by computational chemistry methods that model the geometries of the low-energy isomers of the tag complexes, is used to assign the absolute configuration of the analyte. Intensity changes in the rotational spectrum between measurements using racemic and enantiopure tag samples are used to determine the enantiomeric excess. A key feature of chiral tag rotational spectroscopy is that chiral analysis can be performed without any reference samples of the analyte.
Membraneless organelles, also known as biomolecular condensates, formed via liquid-liquid phase separation (LLPS), have been proposed to play essential roles in diverse cellular processes. Their dysregulation has been implicated in various neurodegenerative diseases, highlighting the need to understand the principles governing their formation. A key challenge is to decode the sequence-encoded rules that tune the thermodynamics and dynamics of biomolecular condensation. Alongside experimental advances, computational modeling at mesoscopic, coarse-grained, and atomistic resolutions has emerged as a powerful approach to probe LLPS. In this review, we summarize recent progress in the predictive modeling of biomolecular phase separation, with a focus on residue-level coarse-grained models that serve as a bridge between mesoscopic models used in field-theoretic simulations and atomistic models. We highlight the approaches adopted in developing models to study LLPS and provide a perspective on directions for future improvement. We conclude by proposing a parameterization strategy that combines multiscale simulations with experimental approaches to uncover the molecular mechanisms underlying condensate formation, maturation, and dysfunction.
This review describes insights obtained from recent studies of unimolecular and bimolecular reactions of small carbenes in the gas phase and cryogenic environments. Following a description of what determines the singlet-triplet splitting in carbenes, we discuss the challenges involved in producing carbenes in concentrations sufficient for studying their reactions. We document the methods developed for their preparation and the array of spectroscopic techniques available for their characterization. The review emphasizes recent progress in studies of hydroxycarbenes and small alkyl carbenes that easily isomerize to more stable isomers. The studies of unimolecular reactions of hydroxycarbenes show how quantum mechanical tunneling determines their lifetimes. A new carbonyl-ene mechanism has been demonstrated in the biomolecular reactions of hydroxymethylene and methylhydroxycarbenes. We evaluate the impact of these new results on chemical processes relevant to atmospheric, planetary, and interstellar environments and highlight the importance of collaboration between theory and experiment in interpreting mechanisms.
Coupling molecules to the quantized radiation field inside an optical cavity creates a set of new photon-matter hybrid states, so-called polaritons. Recent experiments have demonstrated that molecular polaritons can lead to modifications of excited-state dynamics and spectroscopy, photochemistry, and ground-state chemical reactivities. We review the fundamental theory of molecular polaritons under collective light-matter coupling, where many molecules are simultaneously coupled to the cavity mode. Our discussion is based on model systems that effectively capture the essential physics of experiments, allowing one to obtain analytic theories and valuable insights into the microscopic mechanisms in polariton dynamics and spectroscopy, photochemistry, and vibrational strong coupling-modified chemistry.
Over the past few decades, radiofrequency ion traps have become an attractive platform for studying chemical reactions as they enable a high degree of control over ion-molecule dynamics. In this review, we summarize techniques for the trapping and cooling of atomic and molecular ions in radiofrequency traps, including Doppler and resolved-sideband laser cooling, sympathetic cooling, and cryogenic buffer-gas methods. We discuss strategies for controlling key reaction parameters: the preparation of specific internal quantum states by internal cooling, optical pumping, state-selective photoionization and quantum logic spectroscopy; the manipulation of collision energies through micromotion control, dynamic trapping, and combination with molecular beams; and the selection of molecular structure via isotopic substitution, conformational separation, and isomer-specific ion generation. We illustrate applications of these approaches by discussing studies on quantum-state-dependent kinetics, quantum resonance effects, and structure-sensitive reactivity in ion-neutral collisions. We conclude by outlining future challenges, including full state-to-state reaction mapping, reaching the ultracold quantum regime free of micromotion, and the exploration of complex and chiral systems.
Quantum computing offers the promise of revolutionizing quantum chemistry by enabling the solution of chemical problems for substantially less computational cost. While most demonstrations of quantum computation to date have focused on resolving the energies of the electronic ground states of small molecules, the field of quantum chemistry is far broader than ground state chemistry; equally important to practicing chemists are chemical reaction dynamics and reaction mechanism prediction. Here, we review progress toward and the potential of quantum computation for understanding quantum chemistry beyond the ground state, including for reaction mechanisms, reaction dynamics, and finite temperature quantum chemistry. We discuss algorithmic and other considerations these applications share, as well as differences that make them unique. We also highlight the potential speedups these applications may realize and challenges they may face. We hope that this discussion stimulates further research into how quantum computation may better inform experimental chemistry in the future.
RNA function is deeply intertwined with its conformational dynamics. In this review, we survey recent advances in the use of atomistic molecular dynamics simulations to characterize RNA dynamics in diverse contexts, including isolated molecules and complexes with ions, small molecules, or proteins. We highlight how enhanced sampling techniques and integrative approaches can improve both the precision and accuracy of the resulting structural ensembles. Finally, we examine the emerging role of artificial intelligence in accelerating progress in RNA modeling and simulation.
This review concerns light-to-chemical energy conversion, focusing on approaches that could be driven by terrestrial sunlight to produce hydrogen and/or reduce carbon dioxide. Recent advances in photocatalytic (PC) and photoelectrocatalytic (PEC) materials are covered. In both approaches, the electron-hole pairs that are created by photon absorption must travel in specific directions to the sites that mediate multielectron bond making/breaking redox reactions. Thermodynamic requirements for materials stability are described, although some recently discovered materials appear to be exceptions. For PC materials, the importance of rate matching between reduction and oxidation processes and the mass transfer of intermediates and products is emphasized. Surprisingly, metal sulfides appear to be promising for PC carbon dioxide reduction. For PEC materials, recent work elucidating the elementary step mechanism for oxygen evolution on metal oxides and the discovery of chalcogen-based photocathode materials capable of sustained light-driven CO2 reduction are discussed.
Recent advancements in transmission electron microscopy (TEM) have substantially expanded our capability to observe nanocrystals at unprecedented spatial and temporal resolutions. Innovations in TEM instruments, specimen preparation, and imaging modality have overcome historical limitations related to radiation damage, weak contrast for light elements, 2D projection limitations, and high-vacuum constraints. Additionally, advanced image processing techniques, particularly those incorporating machine learning, have enhanced data interpretation by enabling denoising, segmentation, and quantitative analysis. These advancements now enable the atomic-scale visualization of structural motifs, defects, strain distributions, and dynamic structural transformations of nanocrystals in realistic environments, including liquids and gases. The integration of these emerging TEM techniques promises novel insights into nanoscale processes that directly link atomic structure and dynamics to functional properties, thus significantly advancing the ultimate goal of materials by design.
Ultrafast core-to-valence transient absorption spectroscopy has emerged as a powerful technique for monitoring nonequilibrium chemical dynamics with element and site specificity. Owing to advancements in the robust, tabletop generation of ultrafast extreme ultraviolet (XUV) and soft X-ray (SXR) pulses, this technique has been applied to great effect in investigating electronic excited-state dynamics in various gas-phase molecules. This review begins with an overview of the experimental advances that have enabled laboratory-scale XUV and SXR production with particular emphasis on high-harmonic generation, central to modern implementations of tabletop core-to-valence transient absorption spectroscopy. We then highlight a collection of landmark studies that demonstrate the unprecedented insights this technique yields into the site-specific excited-state dynamics governing photoinduced processes such as bond dissociation, conformational change, and electronic relaxation in gas-phase molecules. We conclude with an outlook on future frontiers, including control of excited-state dynamics, other nonlinear X-ray spectroscopies, and next-generation light sources.
Complex spatiotemporal correlations direct heterogeneous reactions spanning from the atomic- to meso-length scales with illustrations ranging from single-molecule adsorption to the oxidation of graphitic materials. Capturing the on-surface dynamics that underpin such processes benefits from spatially resolved and real-time in situ characterization of surface morphologies and adsorbed species, especially when paired with molecular scattering systems that provide tight control of incident molecular energy and approach geometry. Direct visualization shows that site-specific reactivity, correlated surface fluctuations, and structurally dependent reaction rates are interrelated to the on-surface fate of scattered species. Recent advances in neutral helium atom scattering are also presented as pathways for elucidating surface electron-phonon coupling dynamics. Overall, experiments presented herein represent a new direction for the interrogation of on-surface dynamics in which incident kinematics and energetics are tunable control parameters that influence time-evolving surface dynamics-and provide an incisive complement to traditional scattering experiments that monitor volatile products and scattered species.
