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The rhenium-containing molecules ReC, ReN, ReO, ReS, and ReC2 have been investigated using a pulsed laser ablation supersonic beam molecular source in resonant two-photon ionization experiments with time-of-flight mass spectrometric detection. Sharp predissociation thresholds have been observed, allowing precise bond dissociation energies (BDEs) to be measured as D0(ReC) = 5.731(3) eV, D0(ReN) = 5.635(3) eV, D0(ReO) = 5.510(3) eV, D0(ReS) = 3.947(3) eV, and D0(Re–C2) = 5.359(3) eV. The threshold for two-photon ionization was also measured for ReC, ReN, and ReO, providing ionization energies (IEs) of IE(ReC) = 8.425(12) eV, IE(ReN) = 8.193(20) eV, and IE(ReO) = 8.561(11) eV. These are the first measurements of these thermochemical quantities to be reported in the literature. The combination of BDEs and IEs allowed the BDEs of the cations ReC+, ReN+, and ReO+ to be determined via a thermochemical cycle as D0(Re+-C) = 5.140(12) eV, D0(Re+-N) = 5.275(20) eV, and D0(Re+-O) = 4.783(11) eV. In addition, computations of these thermochemical values were performed using density functional theory [B3LYP/aug-cc-pVQZ(-PP)] to determine the ground states and their geometric parameters. These were further studied at the CCSD(T) level with extrapolation to the complete basis set limit using aug-cc-pVXZ(-PP) basis sets (X = 3, 4, 5) to obtain computational values of the BDEs and IEs as well. The high-level super correlation consistent composite approach (s-ccCA) was also utilized, providing an additional approach for the prediction of thermochemical values. The electronic structure of the molecules is discussed, along with the periodic trends as the ligand is varied. 

Following the global regulation of legacy PFAS molecules, fluorotelomer molecules have been widely employed as replacements to PFOS in aqueous film-forming foam (AFFF) and PFOA in other products. Recent field studies indicate that fluorotelomer molecules are increasingly identified in environmental settings including groundwater, soil and sediments. Consequently, gaining a comprehensive understanding of the fate and transport of fluorotelomers in soils and sedimentary environments is vital. In this study, the behavior of two different fluorotelomers, 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTS and 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTC, in three common soil minerals (kaolinite, montmorillonite and illite) having quite different interfacial properties are reported using molecular dynamics simulations. The interfacial adsorption and dynamical characteristics of 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTS and 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTC vary substantially between the three minerals. Irrespective of the mineral composition, 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTS exhibits surface complexation while 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTC coordinates only with neutral and low charged clay minerals. In addition, the fundamental interactions that dictate the adsorption, interfacial structure of 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTS and 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTC are completely different for the three minerals. The large, aggregated clusters of 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTS at the surface experienced greater stability for longer periods of time and restricted mobility than 6[thin space (1/6-em)]:[thin space (1/6-em)]2 FTC for all three clay minerals. Importantly, the current study provides cluster size dependent diffusion behavior of surface adsorbed fluorotelomer molecules in each clay mineral. Such detailed mechanistic insights are necessary to understand the environmental footprint of fluorotelomers around contaminated sites. 

The correlation consistent basis sets (cc-pVnZ with n = D, T, Q, 5) for the Ga–Br elements have been redesigned, tuning the sets for use for density functional approximations. Steps to redesign these basis sets for an improved correlation energy recovery and efficiency include truncation of higher angular momentum functions, recontraction of basis set coefficients, and reoptimization of basis set exponents. These redesigned basis sets are compared with conventional cc-pVnZ basis sets and other basis sets, which are, in principle, designed to achieve systematic improvement with respect to increasing basis set size. The convergence of atomic energies, bond lengths, bond dissociation energies, and enthalpies of formation to the Kohn–Sham limit is improved relative to other basis sets where convergence to the Kohn–Sham limit is typically not observed. 

Ether-based PFAS, such as ADONA, show a unique influence on their adsorption properties with different mineral interfaces. 

Abstract Vibrational spectroscopy enables critical insight into the structural and dynamic properties of molecules. Presently, the majority of theoretical approaches to spectroscopy employ wavefunction‐basedab initioor density functional methods that rely on the harmonic approximation. This approximation breaks down for large molecules with strongly anharmonic bonds or for molecules with large internuclear separations. An alternative to these methods involves generating molecular anharmonic potential energy surfaces (potentials) and using them to extrapolate the vibrational frequencies. This study examines the efficacy of density functional theory (DFT) and the correlation consistent Composite Approach (ccCA) in generating anharmonic frequencies from potentials of small main group molecules. Vibrational self‐consistent field Theory (VSCF) and post‐VSCF methods were used to calculate the fundamental frequencies of these molecules from their potentials. Functional choice, basis set selection, and mode‐coupling are also examined as factors in influencing accuracy. The absolute deviations for the calculated frequencies using potentials at the ccCA level of theory were lower than the potentials at the DFT level. With DFT resulting in bending modes that are better described than those of ccCA, a multilevel DFT:ccCA approach where DFT potentials are used for single vibrational mode potentials and ccCA is used for vibrational mode‐mode couplings can be utilized for larger polyatomic systems. The frequencies obtained with this multilevel approach using VCIPSI‐PT2 were closer to experimental frequencies than the scaled harmonic frequencies, indicating the success of utilizing post‐VSCF methods to generate more accurate representations of computed infrared spectra. 

Recent advances in strong light−matter interactions have revealed a wealth of new physical phenomena in molecules embedded in optical cavities, including modified chemical reactivity, altered excitation spectra, and novel quantum correlations. To describe these effects from first-principles, the field of ab initio quantum electrodynamics (QED) has emerged as a compelling extension of quantum chemistry that treats electronic and photonic degrees of freedom on equal footing. In this Perspective, we review the growing landscape of many-body QED methods, including Hartree−Fock, density functional theory (QEDFT), timedependent DFT (QED-TDDFT), configuration interaction (QED-CI), complete active space (QED-CASSCF), coupled cluster (QED-CC), quantum Monte Carlo (QED-QMC), and density matrix renormalization group (QED-DMRG), highlighting recent developments and implementations. We further explore real-time methods, gradient and Hessian formalisms, and the integration of nonadiabatic nuclear dynamics. Applications range from benchmark simulations of polaritonic chemistry to quantum simulations on emerging quantum hardware. We conclude by outlining future directions for theory development and interdisciplinary efforts at the interface of quantum chemistry, condensed matter, and quantum optics. 

As the year-to-year gains in speeds of classical computers continue to taper off, computational chemists are increasingly examining quantum computing as a possible route to achieve greater computational performance. Quantum computers, built upon the properties of superposition, interference, and entanglement of quantum bits, offer, in principle, the possibility to outperform classical computers for solving many important classes of problems. In the field of chemistry, quantum algorithm development offers promising propositions for solving classically intractable problems in areas such as electronic structure, chemical quantum dynamics, spectroscopy, and cheminformatics. However, physical implementations of quantum computers are still in their infancy and have yet to outperform classical computers for useful computations. Still, quantum software development for chemistry is a highly active area of research. In this perspective, we summarize recent progress in the areas of quantum computing algorithms, hardware, and software, and we describe the challenges that remain for useful implementations of quantum computing for chemical applications. 

The discrepancy in single referenceversusmultireference guess orbitals in the strongly correlated LuN.