Wheelermacgregor6843

We report on the experimental observation of the B+ 2Σ+ state of MgAr+ located below the Mg+(3p 2P3/2) + Ar(1S0) dissociation asymptote. Using the technique of isolated-core multiphoton Rydberg-dissociation spectroscopy, we have recorded rotationally resolved spectra of the B+ 2Σ+(v') ← X+ 2Σ+(v″ = 7) transitions, which extend from the vibrational ground state (v' = 0) to the dissociation continuum above the Mg+(3p 2P3/2) + Ar(1S0) dissociation threshold. The analysis of the rotational structure reveals a transition from Hund's angular-momentum-coupling case (b) at low v' values to case (c) at high v' values caused by the spin-orbit interaction. Measurements of the kinetic-energy release and the angular distribution of the Mg+ fragments detected in the experiments enabled the characterization of the dissociation mechanisms. The vibrational levels of the B+ state above v' = 6 are subject to predissociation into the Mg+(3p 2P1/2) + Ar(1S0) continuum, and the fragment angular distributions exhibit anisotropy β parameters around 0.5, whereas direct dissociation into the continuum above the Mg+(3p 2P3/2) + Ar(1S0) asymptote is characterized by β parameters approaching 2. Molecular ions excited to the B+ state with v' = 0-6 efficiently absorb a second photon to the repulsive part of the 2Σ+ state associated with the Mg+(3d 2D3/2,5/2) + Ar(1S0) continua. The interpretation of the data is validated by the results of ab initio calculations of the low-lying electronic states of MgAr+, which provided initial evidence for the existence of bound vibrational levels of the B+ state and for the photodissociation mechanisms of its low vibrational levels.We develop a full-quantum formulation of constrained nuclear-electronic orbital density functional theory (cNEO-DFT). This formulation deviates from the conventional Born-Oppenheimer framework, and all nuclei and electrons are treated on an equal footing within the molecular orbital picture. Compared to the conventional DFT, the ground state energy in full-quantum cNEO-DFT inherently includes all vibrational zero-point energies. We also derived and implemented the analytic gradient of the full-quantum cNEO-DFT energy with respect to the quantum nuclear expectation positions. With the analytic gradient, the geometry optimizations are performed, which naturally include the nuclear quantum effects and describe the geometric isotope effects. The full-quantum cNEO-DFT is tested on a series of small molecules and the transition states of two hydrogen transfer reactions. The results are compared with those from conventional DFT, DFT-VPT2, and NEO-DFT with only key protons treated quantum mechanically. It is found that the nuclear quantum effects have notable impacts on molecular equilibrium geometries and transition state geometries. The full-quantum cNEO-DFT can be a promising method for describing the nuclear quantum effects in many chemical processes.We report a global study of the 3p Rydberg complex of the MgAr+ molecular ion. High-resolution spectroscopic data on the two spin-orbit components of the A+ electronic state were obtained by isolated-core multiphoton Rydberg-dissociation spectroscopy up to vibrational levels as high as v' = 29, covering more than 90% of the potential wells. Accurate adiabatic potential-energy functions of the A+ and B+ states, which together form the 3p Rydberg complex, were obtained in a global direct-potential-fit analysis of the present data and the extensive data on the B+ state reported in Paper I [D. Wehrli et al., J. Chem. Phys. 153, 074310 (2020)]. The dissociation energies of the B+ state, the two spin-orbit components of the A+ state, and the X+ state of MgAr+ are obtained with uncertainties (1 cm-1) more than two orders of magnitude smaller than in previous studies.The anapolar response of a molecule exposed to a nonhomogeneous magnetic field B with spatially uniform curl C = ∇ × B is rationalized via second-rank tensors, a nonsymmetric aαβ, and a symmetric bαβ, referred to as static anapole magnetizabilities, which can be evaluated by quantum-mechanical Rayleigh-Schrödinger perturbation theory or allowing for the definitions of electronic current densities JB(r) and JC(r) induced in the electron cloud. The isotropic part of bαβ is even under the fundamental symmetry operations of charge conjugation C, parity P, and time reversal T and does not vanish for all matter and antimatter. The isotropic part of aαβ is even under C and T, but odd under P, and is exhibited only by chiral compounds. In the presence of optical fields, represented for simplicity by a monochromatic plane wave of frequency ω, dynamic anapole magnetizabilities and various anapole polarizabilities are taken into account. Assuming, within the electric quadrupole approximation for the impinging wave, that the electric field at the origin of the coordinate system is E(0), with uniform gradient ∇E, and magnetic field is B, the anapolar response is interpreted by second-rank aαβ(ω), aαβ'(ω), fαβ(ω), fαβ'(ω) and third-rank gα,βγ(ω), gα,βγ'(ω) frequency-dependent tensors. The same basic definitions are arrived at introducing frequency-dependent electronic current densities JB(r, ω) and JC(r, ω). As the frequency-dependent anapole susceptibilities depend on the origin of the coordinate system, relationships connecting them for two different origins are reported.Vacancy and self-interstitial atomic diffusion coefficients in concentrated solid solution alloys can have a non-monotonic concentration dependence. Here, the kinetics of monovacancies and ⟨100⟩ dumbbell interstitials in Ni-Fe alloys are assessed using lattice kinetic Monte Carlo (kMC). The non-monotonicity is associated with superbasins, which impels using accelerated kMC methods. Detailed implementation prescriptions for first passage time analysis kMC (FPTA-kMC), mean rate method kMC (MRM-kMC), and accelerated superbasin kMC (AS-kMC) are given. The accelerated methods are benchmarked in the context of diffusion coefficient calculations. The benchmarks indicate that MRM-kMC underestimates diffusion coefficients, while AS-kMC overestimates them. In this application, MRM-kMC and AS-kMC are computationally more efficient than the more accurate FPTA-kMC. Our calculations indicate that composition dependence of migration energies is at the origin of the vacancy's non-monotonic behavior. Tirzepatide in vivo In contrast, the difference between formation energies of Ni-Ni, Ni-Fe, and Fe-Fe dumbbell interstitials is at the origin of their non-monotonic diffusion behavior.