We present vibe-qc, a general-purpose open-source electronic-structure code for molecules and solids, developed almost entirely with agentic AI under expert human direction. The code is released under the Mozilla Public License 2.0 (MPLv2). The implementation comprises a C++17 numerical core and Python calculation drivers. Molecular methods include Hartree-Fock, Kohn-Sham DFT, Møller-Plesset theory and double hybrids, coupled cluster, active-space methods, and excited states. Dispersion corrections, continuum solvation, and effective core potentials are also available. Periodic calculations use Gaussian-basis HF and DFT with Brillouin-zone sampling. Molecular and periodic method coverage differs; the feature matrices specify analytic and numerical derivatives and distinguish validated and experimental implementations. The validation set is a key contribution of this work. It combines independent program comparisons, published benchmarks, and internal consistency tests. Molecular mean-field energies agree at the nanohartree scale, and conventional CCSD(T) energies agree within 3.3 × 10 - 7 E h for the tested systems. Local-correlation and periodic limitations are reported with the comparisons. Numerical results, calculation metadata, and analysis scripts are supplied as machine-readable Supporting Information. The independently maintained vibe-view viewer, vibe-queue scheduler, and qvf toolkit support visualization and job management; trexio provides wavefunction interchange.

We employed advanced quantum chemical methods to investigate the electronic properties of five widely consumed psychostimulants: nicotine, cotinine, caffeine, theophylline, and theobromine. Molecular geometries were optimized in an aqueous environment using density functional theory (DFT) with the B3LYP exchange-correlation functional and an extensive basis set. The calculated structures showed excellent agreement with experimentally determined solid-state structures deposited in the Cambridge Crystallographic Data Centre (CCDC). Full vibrational analyses enabled the determination of thermodynamic properties, including Gibbs energies. For the neutral ground states, we calculated dipole and quadrupole moments, dipole polarizabilities, zero-point vibrational energies, and entropic contributions. Adiabatic ionization energies and electron affinities were obtained from optimized cationic and anionic geometries and used to derive molecular electronegativities, chemical hardnesses, and electrophilicity indices. Reaction Gibbs energies for ionization and reduction were converted into absolute oxidation and reduction potentials. To improve accuracy, we additionally employed the highly correlated DLPNO-CCSD(T) method for ionization energies and electron affinities in water. Finally, the electronic and global properties of biologically relevant protonated forms nicotinium, cotinium, caffeinium, theophyllinium, and theobrominium were investigated, providing a description of these compounds in aqueous solution. This approach enabled comparison of their structural, thermodynamic, electronic, and redox properties across the investigated molecular series. In addition to the implicit Conductor-like Polarizable Continuum Model (CPCM), an explicit solvation approach involving several water molecules was also tested for the nicotine-water aggregate.

We show that a discrete quantization law for cosmological entropy emerges naturally within a meta-geometric gauge theory of gravity, when the standard de Sitter entropy relation is combined with the topological structure of the theory. Our framework is based on a pre-metric action containing a MacDowell-Mansouri term with a spontaneously broken (A)dS gauge symmetry reduced to the Lorentz subgroup. We derive an inverse proportionality between the topological θ-angle and the cosmological constant, which enforces a topological quantization condition. As a consequence, the de Sitter entropy becomes quantized and scales linearly with a topological quantum number. This quantization provides a natural entropic stabilizer and a quantum topological protection for a large cosmological constant, thereby offering a microscopic gauge-theoretic realization of the holographic naturalness conjecture. We also discuss possible emergence of the N-portrait in cosmology and a dynamical relaxation of the vacuum energy.

Relativistic extensions of de Broglie-Bohm theory postulate a preferred foliation of spacetime, an additional structure essential for defining simultaneous configurations on Minkowski spacetime but conventionally believed to be empirically undetectable at quantum equilibrium. In this paper, we outline an experimental protocol for empirically detecting the preferred foliation, which is assumed to be flat for simplicity. Building on the arrival-time distributions for spin-1/2 particles predicted by Das and Dürr, we show that, in an Einstein-Podolsky-Rosen-Bohm-type experiment with spacelike-separated spin and arrival-time measurements, the observed arrival-time statistics will depend crucially on the temporal order of these measurements relative to the preferred foliation of spacetime. This dependence offers a potential experimental signature of the preferred foliation postulated by relativistic Bohmian models. Moreover, it implies the possibility of superluminal signaling.

Jaynes' maximum entropy (MaxEnt) principle selects, from all probability distributions consistent with a set of constraints, the one that maximizes the Shannon entropy. The principle is well-defined for classical, real-valued probabilities, but extending it to complex-valued probability theories requires care. Youssef's complex probability framework, in which quantum mechanics is reformulated as a Bayesian theory with complex amplitudes and the observable probability is the squared modulus (Born rule), does not admit a natural MaxEnt extension: the L2 normalization of that framework is incompatible with the L1 normalization assumed by Shannon entropy, and the resulting complex-valued entropy functional cannot be maximized without additional structure absent from Youssef's axioms. The present paper proposes a different extension of Kolmogorov's axioms to the complex domain, replacing non-negativity with the condition that the real part of every probability be non-negative. This framework, which retains L1 normalization and recovers classical probability when the imaginary part vanishes, admits a natural MaxEnt principle: the real part of the complex Shannon entropy is a well-posed real functional, its Euler-Lagrange equations produce an explicit complex Gibbs distribution with complex Lagrange multipliers, and the classical Gibbs distribution is recovered as the special case of real multipliers. The die problem (Jaynes' Brandeis dice example) is worked out in detail for both the fair and the loaded cases, illustrating how imaginary constraints redistribute the observable probability mass in a way that has no counterpart in classical MaxEnt.

Wireless sensor networks (WSNs) are pervasively employed in critical domains such as smart healthcare, industrial automation, and environmental surveillance, where secure access control is essential. User authentication protocols are vital for thwarting unauthorized intrusions, yet the vast majority of existing schemes rely on conventional public-key cryptography (such as ECC, RSA), which is provably insecure in the post-quantum era due to Shor's algorithm. This motivates the design of post-quantum authentication that is also lightweight for resource-limited sensors. To address this challenge, we propose an efficient authentication and key agreement protocol based on Number Theory Research Unit (NTRU), a lattice-based cryptosystem offering proven resistance to quantum attacks. We have proven the correctness and security of our scheme through BAN logic and random oracle model and demonstrated through informal analysis that our scheme can resist various attack methods and possesses high security features. Moreover, we thoroughly evaluate our protocol against the most recent state-of-the-art schemes. The results indicate that our scheme has the lowest computational cost, and its communication cost is superior to that of most other schemes. Overall, our proposed protocol provides a robust, efficient, and future-proof authentication solution for WSNs, well-suited for deploying WSNs environments.

In a comparative study, we re-evaluate the complex Hg-O bonding behavior on the examples of isolated Hg-O anions in several new oxidomercurate compounds of alkali metals, together with their crystal structures and details on the respective syntheses. For the oxidomercurate(II) Li2HgO2, a new tetragonal structure type was established with Li+ in distorted tetrahedral oxygen coordination. Li2HgO2 was obtained from the reaction of Li2O and HgO at 500 °C. The crystal structure model was derived from powder X-ray diffraction data. The new oxidomercurates(0) Rb2HgO and Cs2HgO crystallize isotypically in a new monoclinic structure and form a solid solution Rb2-xCsxHgO. The K-substituted Rb compound Rb1.81(2)K0.19(2)HgO crystallizes in the same structure type, whereas Cs1.782(5)K0.218(5)HgO adopts a different, new orthorhombic structure type. All oxidomercurates(0) A2HgO were prepared from mixtures of metal A and HgO at 300-325 °C. The crystal structure models are based on single-crystal X-ray diffraction data. Solid-state density functional theory (DFT) and molecular-level quantum-chemical calculations show that the A2HgO compounds are oxidomercurates(0) containing the quasimolecular anion [HgO]2-. A detailed comparison of the Hg-O bonding in [HgO]2- and [HgO2]2- was performed and shows predominantly covalent Hg-O interactions involving Hg 5d, 6s, and 6p states. The computational results are corroborated by the accordance of calculated and experimental vibrational spectra of Li2HgO2.

The chemical vapor deposition (CVD) of two-dimensional (2D) materials proceeds through a complex cascade of nonequilibrium, high-temperature surface reactions. Atomistically resolving such dynamically evolving vapor-solid interfaces remains a major challenge in both in situ experimental detection and theoretical simulations of time-dependent aggregation coupled with covalent-bond formation at the atomic scale. Here, we develop a chemistry-aware active-learning distillation (Chem-ALD) framework to construct computationally efficient, high-fidelity machine-learning force fields (MLFFs) with near quantum-chemical accuracy. By deploying the CVD-MLFF across distinct prototypical CVD systems-graphene and h-BN-on different substrates, we reveal a universal, nonclassical nucleation pathway governed by a generic multitransition states (MTSs) mechanism. Fundamentally bypassing the single-step barrier assumed by classical nucleation theory, this MTS pathway proceeds through the continuous evolution of highly fluctuating intermediates: the assembly of vapor precursors into nanochains, their progressive coalescence into branched networks, and a rate-determining transformation into critical "nano-sea-star-like" structures. In the subsequent postnucleation stage, a hexagonal nanoplatelet crystallite emerges within a fractal-like intermediate. This continuous evolution relies on the "nano-sea-star-like" topology acting as a universal kinetic funnel that connects surrounding transient states. By mapping these complex reactive landscapes at an atomistic resolution, our framework yields a unified physical picture linking localized transition-state kinetics to the macroscopic, wafer-scale synthesis of 2D single crystals.

Quantum-matter theory (QMT), based on the Schrödinger or Dirac equations, is firmly established for both intra- and intermolecular interactions. However, there are two key issues with QMT. First, its applicability to large molecular complexes is hindered by the relatively high computational cost of the calculations required to achieve high accuracy. Second, fields are also quantum objects that produce many intriguing effects beyond standard QMT approaches to molecular systems. This review focuses on recent developments in quantum-field theory (QFT) approaches to both covalent and noncovalent interactions for molecules in vacuum and subject to environments such as cavities and solvents. QFT provides a rich playground for novel chemical theories and insights. For example, chemical reactions and van der Waals interactions can be manipulated by cavities, boundaries, and optical excitations; novel interactions emerge when molecules interact with quantized fields; systems with millions of atoms could soon be treated with coarse-grained QFT formalisms; and unexpected scaling laws for atomic and molecular properties can emerge when QFT is applied to sets of chemical systems. This review sets the stage for an exciting QFT-driven path for further development of chemical theory.

Intrinsically disordered molecular systems, such as random copolymers and intrinsically disordered proteins, exhibit scale-invariant, power-law cluster distributions that cannot be explained by conventional mean-field theories. A fundamental challenge is to understand how sequence randomness, which cannot be averaged into effective parameters, drives the formation of such polydisperse assemblies. Using a minimal coupled field theory that explicitly links a conserved density field to a nonconserved "junction" field representing stochastic binding site density, we show that the attraction between two fields χ, together with the fluctuations in the junction field Tϵ, renormalizes the effective interfacial tension to negative values: Δγ ∼ -Tϵχ2. This negative interfacial tension suppresses coalescence and stabilizes a scale-invariant ensemble of clusters with a power-law size distribution, as confirmed by both numerical calculations and coarse-grained simulations of sequence-disordered biomolecules, and are consistent with diverse experimental observations. Our work reveals a general physicochemical mechanism by which intrinsic molecular disorder and fluctuations jointly govern phase separation in systems with built-in randomness, providing a unifying, chemistry-oriented framework for understanding and engineering heterogeneous soft matter systems.

Electrostatic protein-pigment interactions have been implicated in tuning the electron transfer chemistry of chlorophylls in vivo; however, these effects are difficult to probe directly, leading to a dearth of experimental data that limits our understanding. Herein, we report a chlorophyll model compound based on a Mg-porphyrin framework with a secondary coordination sphere designed to probe isolated electrostatic interactions with the porphyrin macrocycle. Protonation of two second-sphere amine groups led to a significant increase in the redox potential of the porphyrin ring, drawing a strong analogy to the postulated influence of protonated amino acids on the properties of chlorophylls in vivo. Experimental techniques (electronic absorption spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry) were complemented by density functional theory calculations to uncover the impact of the proximal charged substituents on the electronic structure of the Mg-porphyrin complex. 1-electron oxidation of the protonated complex yielded the corresponding π-cation radical complex, which mimicked the reaction between photo-oxidized chlorophyll and tyrosine during photosynthesis by rapidly oxidizing phenolic substrates to yield phenoxyl radicals via electron-transfer-limited proton-coupled electron transfer. Overall, this work lends strong experimental support for the role of local protein electrostatics in achieving high-potential chlorophyll-based oxidants in Nature.

Intramolecular hydrogen-bonded networks have been designed and synthesized to control quinone redox thermodynamics in a family of anthraquinone (AQ) derivatives. The networks contain imidazole fused to AQ, which is hydrogen-bonded to the AQ carbonyl, and the extended motifs include phenol (P) and benzimidazole (BI). Cyclic voltammetry reveals a systematic anodic displacement of the AQ/AQ•- couple as the hydrogen-bonded network is extended, resulting in a cumulative +440 mV shift. Visible spectroelectrochemistry provides direct reduced-state markers: AQ exhibits AQ•- bands at ∼410 and ∼539 nm, whereas the intramolecular hydrogen-bonded constructs display only blue-shifted AQ•- signatures at ∼490 nm (BI-AQ), ∼505 nm (BIP-AQ), and ∼494 nm (BI2P-AQ), consistent with hydrogen-bond-dependent perturbation of the reduced quinone electronic structure. Infrared spectroelectrochemistry further resolves the underlying hydrogen-bonding interactions, revealing depletion of the neutral AQ ν(C═O) band (∼1667 cm-1) under reductive polarization with the emergence of hydrogen-bonded AQ•- band at ∼1480 cm-1 in the AQ derivatives. Oxidative polarization, yielding the phenoxyl radical, induces benzimidazolium formation and a blue-shifted AQ ν(C═O) band (∼1678 cm-1), highlighting the directional dependence of the perturbation and the role of the AQ carbonyl as a reporter of the interaction with the intramolecular hydrogen-bonded network. Treating the hydrogen-bonding protons quantum mechanically, nuclear-electronic orbital density functional theory calculations show strengthening of the hydrogen bonds cooperatively across the network upon one-electron reduction and oxidation, correctly predicting the observed stabilization of the AQ•- state. These fundamental insights will assist in the design of more precisely tuned catalysts.

Altermagnetism (AM) has been theoretically predicted to arise widely in T2OCh2 (T = 3d transition metal; Ch = S, Se, Te) layers, offering opportunities for unconventional spin-dependent electronic phenomena. However, experimental realization of AM in this family remains scarce. Recently, spin-split electronic bands have been observed using surface-sensitive photoemission spectroscopy in the 1221-type, vanadium-based compounds KV2Se2O and Cs1-δV2Te2O, where the T2OCh2 layer and alkali metal are alternately stacked. Nevertheless, their altermagnetic spin splitting is compensated between adjacent layers and therefore vanishes in the bulk. Here, we report AM in a new 1221-type chromium-based compound, CsCr2S2O. It undergoes antiferromagnetic ordering at 326 K, followed by a metal-to-insulator transition (MIT) at 305 K. The antiferromagnetism (AFM) adopts a C-type configuration, satisfying the spin space symmetry required for AM. Across the MIT, a structural modulation with propagation vector q = (1/2, 1/2, 0) emerges, accompanied by Cr charge disproportionation and magnetic modulation, while preserving the altermagnetic spin splitting. Our comprehensive experiments and density functional theory (DFT) calculations reveal the cooperative interplay among lattice distortion, magnetic ordering, and electronic correlations underlying the Verwey-type MIT. The Verwey-type transition between metallic and insulating altermagnetic states in CsCr2S2O offers a unique opportunity to explore multifunctional charge- and spin-based applications and to study emergent collective electronic states associated with AM.

Ubiquitin (Ub) conjugating enzymes (E2s) are central to Ub signaling, yet their systematic activity-based profiling remains challenging because of the weak nucleophilicity and elevated pKa of their catalytic cysteines. Existing Ub probes primarily target deubiquitinases (DUBs), and the only reported E2-targeting probe requires E1-dependent activation to capture limited E2s. To profile E2s broadly, here, Ub chloromethylketone (UbCMK) is reported as a standalone activity-based probe. Density functional theory calculations identified CMK as a highly electrophilic warhead with a low activation barrier for reaction with weakly nucleophilic thiolates. UbCMK was synthesized via activated cysteine-based protein ligation and irreversibly labeled multiple E2s and cysteine DUBs. Activity-based protein profiling and quantitative proteomics in HEK293T cell lysates revealed broad enrichment of E2 enzymes, including many previously inaccessible to other probes. UbCMK furthermore enables activity-dependent quantification of endogenous E2 mobilization across oxidative, proteotoxic, inflammatory, metabolic, lipid oxidative, and genotoxic stress conditions. In addition, UbCMK engages both E1s and DUBs, as well, indicating its broad utility as a probe. Collectively, these results establish UbCMK as a powerful chemical tool that expands activity-based protein profiling coverage across the Ub-proteasome system and enables functional interrogation of E2 enzymes under physiological and pathological conditions.

The pseudomode framework provides an efficient description of open quantum systems in non-Markovian and nonperturbative coupling regimes by utilizing simple Markovian Lindblad master equations that incorporate a set of damped bosonic pseudomodes. Developing an efficient numerical scheme to solve these equations accurately is highly desirable. In this work, we propose a modified multiple Davydov D1 density operator ansatz and combine it with the Dirac-Frenkel time-dependent variational principle to simulate the dynamics governed by these master equations. We apply this variational method to the spin-boson model, both with and without a periodic external driving field, and compute both single- and two-time expectation values in non-Markovian, strong-coupling regimes. The accuracy of our variational approach is validated by comparing its predictions with results obtained from the small matrix path integral method. We demonstrate that the variational and path-integral approaches are in excellent agreement for both single- and two-time expectations across nondriven and driven cases, spanning both low- and high-temperature regimes. Our results establish the reliability and broad applicability of the pseudomode-based variational approach for calculating two-time correlation functions in open quantum systems.