Analytical Quartic Centrifugal Distortion Constants By Fourth-order Rayleigh SchrÖdinger Perturbation Theory

Recent advances in microwave spectroscopy, allowing for the measurement and fitting of thousands of spectral lines for a given chemical system, have prompted a need for high accuracy predictions of spectroscopic constants. The quartic Centrifugal Distortion (CD) constants are derived at fourth-order in Rayleigh-Schr\"{o}dinger Vibrational Perturbation Theory (VPT4). Analytical expressions are presented. The constants are implemented in the CFOUR software package in both an explicit sum-over-states form and the analytical (i.e., algebraic) form. The expression for VPT4 quartic CD can be broken into ten distinct contributions, involving products of force constants, Coriolis constants, and coefficients in the expansion of the inverse moment of inertia tensor. It is considerably more complicated than the VPT2 vibration-rotation interaction constants and the VPT4 sextic CD constants. The quartic CD constants first appear at VPT2. The VPT4 level of approximation introduces corrections that are linear in the vibrational quantum numbers. Approximately linear relationships have been identified in analyses of microwave spectra, which allow for direct comparison with the computed CD constants. The VPT4 quartic CD constants require a partial quartic force field, containing all force constants except those for which all indices are different (i.e., $\phi$$_{ijkl}$). As this truncation of quartic force field is usually computed for VPT2 vibrational frequencies, it will be possible to obtain the CD constants alongside routine VPT2 frequencies with negligible added cost

Two-center three-electron bonding in clnh3 revealed via helium droplet infrared spectroscopy: entrance channel complex along the CL + NH3 → CLNH2 + H reaction

Pyrolytic dissociation of Cl$_{2}$ is employed to dope helium droplets with single Cl atoms. Sequential addition of NH$_{3}$ to Cl-doped droplets leads to the formation of a complex residing in the entry valley to the substitution reaction, Cl + NH$_{3}$ $\rightarrow$ ClNH$_{2}$ + H. Infrared Stark spectroscopy in the NH stretching region reveals symmetric and antisymmetric vibrations of a C$_{3v}$ symmetric top. Frequency shifts from NH$_{3}$ and dipole moment measurements are consistent with a ClNH$_{3}$ complex containing a relatively strong two-center three-electron (2c-3e) bond. The nature of the 2c-3e bonding in ClNH$_{3}$ is explored computationally and found to be consistent with the complexation-induced blue shifts observed experimentally. Computations of interconversion pathways reveal nearly barrierless routes to the formation of this complex, consistent with the absence of two other complexes, NH$_{3}$Cl and Cl-HNH$_{2}$, which are predicted in the entry valley to the hydrogen abstraction reaction, Cl + NH$_{3}$ $\rightarrow$ HCl + NH$_{2}

INFRARED PHOTODISSOCIATION SPECTROSCOPY AND MULTIREFERENCE ANHARMONIC VIBRATIONAL STUDY OF THE HO4+ MOLECULAR CATION

\chem{HO_4^+} has been proposed as an astrochemical sink of oxygen but has never been observed.\footnote{Xavier, G. D.; Bernal-Uruchurtu, M. I.; Hernandez-Lamoneda, R., \textit{J. Chem. Phys.} \textbf{2014}, 141, 5, 081101.} Molecular cations of \chem{HO_4^+} and \chem{DO_4^+} are produced in a supersonic expansion. They are mass-selected, and their infrared photodissociation spectra are measured with the aid of argon-tagging. Previous theoretical studies have modeled these systems as proton-bound dimers of molecular oxygen.\footnote{Xavier, F. G. D.; Hernandez-Lamoneda, R., \textit{PCCP} \textbf{2015}, 17, 16023-16032.} Several conformers were located on the quintet, triplet, and singlet surfaces, differing in energy by, at most, a few thousand wavenumbers; the singlet and triplet conformers have pronounced multiconfigurational character. Our \chem{HO_4^+} is formed in a relatively hot environment, and similar experiments have been shown capable of producing multiple conformers in low-lying electronic states.\footnote{Wagner, J. P.; McDonald, D. C.; Duncan, M. A., \textit{Angewandte Chemie-International Edition} \textbf{2018}, 57, 5081-5085.} None of the predicted \chem{HO_4^+} isomers can be ruled out \textit{a priori} based on energetic arguments. We interpret our spectra with second-order vibrational perturbation theory with resonances (VPT2+K) using quartic force fields based on an economical combination of single- and multi-reference theories. The VPT2+K simulations include the effect of electrical anharmonicity; this is particularly important for transitions involving the shared-proton stretch. Previously unidentified chain structures (H-O-O-O-O) that exist on the singlet and triplet surfaces likely represent the global minima

Tempo-Express, a CBR Approach to Musical Tempo Transformations

The original publication is available at www.springerlink.comIn this paper, we describe a CBR system for applying musically acceptable tempo transformations to monophonic audio recordings of musical performances. Within the tempo transformation process, the expressivity of the performance is adjusted in such a way that the result sounds natural for the new tempo. A case base of previously performed melodies is used to infer the appropriate expressivity. Tempo transformation is one of the audio post-processing tasks manually done in audiolabs. Automatizing this process may, therefore, be of industrial interest.This research has been partially supported by the Spanish Ministry of Science and Technology under the project TIC 2003-07776-C2-02 "CBR-ProMusic: Content-based Music Processing using CBR" and EU-FEDER funds.Peer reviewe

THE O2 + ETHYL REACTION IN HELIUM NANODROPLETS: INFRARED SPECTROSCOPY OF THE ETHYLPEROXY RADICAL

Helium-solvated ethylperoxy radicals (chem{CH_3CH_2OO}•) are formed via the textit{in situ} reaction between ethyl radicals and ~{X}$^{3}$$Sigma$$_{g}$$^{-}$ chem{O_2}. The reactants are captured sequentially through the droplet pick-up technique. Helium droplets are doped with ethyl radical via pyrolysis of di-textit{tert}-amyl peroxide or textit{n}-propylnitrite in an effusive, low-pressure source. A mid-infrared spectrum of ethylperoxy is recorded with species-selective droplet beam depletion spectroscopy. Spectral assignments in the CH stretching region are made via comparisons to second-order vibrational perturbation theory with resonances (VPT2+K) based on coupled-cluster quartic force fields. textit{Gauche} and textit{trans} conformers are predicted to be nearly isoenergetic; however, the spectrum indicates that one dominant conformer is present. Indeed, in several previous studies in our group, where chemical reactions were conducted inside droplets, only a single conformer of the product was observed. Exploration of the ethylperoxy potential energy surface, particularly along the CCOO torsional and CO stretching coordinates, motivates an explanation that is based upon an adiabatic funneling mechanism that leads to the exclusive production of one conformer. The slower torsional degree of freedom is cooled more rapidly than the higher frequency stretching and bending coordinates owing to the stronger coupling between the torsional modes and the collective modes of the helium droplet. The reactants are cooled into the torsional well that stabilizes first during their approach on the PES

ROTAMERS OF ISOPRENE: INFRARED SPECTROSCOPY IN HELIUM DROPLETS AND AB INITIO THERMOCHEMISTRY

Isoprene (\chem{C_5H_8}) is an abundant, reactive tropospheric hydrocarbon, derived from biogenic emissions. A detailed understanding of the spectroscopy of isoprene is therefore desirable. Isoprene monomer is isolated in helium droplets and its infrared spectrum is measured in the CH stretching region. Anharmonic frequencies are predicted by VPT2+K simulations employing CCSD(T) force fields with quadratic (cubic and quartic) force constants computed using the ANO1 (ANO0) basis set. The vast majority of the spectral features can be assigned to trans-isoprene on the basis of these computations. Some features of the higher energy gauche conformer are also assignable, by comparison to experiments using heated isoprene. Convergent ab initio thermochemistry is presented for the isomerization pathway, for which the partition function explicitly accounts for the eigenstates associated with separate, uncoupled one-dimensional potential surfaces for methyl torsion and internal rotation between rotamers. The respective 0 and 298.15 K trans/gauche energy differences are 2.82 and 2.52 kcal/mol, which implies a room temperature gauche population of 2.8\%. Additionally, preliminary spectroscopic results for the OH--$\pi$ complexes between hydroxyl radical and isoprene are presented

Trust Propensity Across Cultures: The Role of Collectivism

Does collectivism influence an individual\u27s willingness to trust others? Conflicting empirical results from past research and the role of trust in international marketing make this question important to resolve. We investigate this question across cultures and at the individual level with four studies using multiple methods. Study 1 establishes correlational evidence between societal-level collectivism and individual-level trust propensity with results from a multi-level analysis of data from over 6,000 respondents in 36 different countries. Study 2 offers an individual-level analysis using the trust game, introducing a more rigorous behavioral outcome variable. Study 3 contributes causal evidence at the individual level based on experiments in both the US and China and offers evidence of social projection as the explanatory mechanism. Finally, Study 4 demonstrates managerial relevance by using advertising to prime collectivism and assessing its effect on trust in the firm

Effect of annealing treatments on the anisotropy of a magnesium alloy sheet processed by severe rolling

The effect of annealing treatments on the normal plastic anisotropy (r-value) of a magnesium alloy, AZ61, processed by severe rolling was investigated. The various annealing treatments produce two effects on microstructure: grain coarsening and slight weakening of the texture. In addition, these treatments produce a noticeable decrease of the anisotropy that was correlated with an increase in strain rate sensitivity and a decrease of work hardening rate. It is concluded that an enhanced contribution of basal slip occurs as a consequence of the annealing treatments.The authors acknowledge the financial support from the CICYT grant MAT 2006-02672 awarded by the Spanish Ministry of Education and Science.Peer reviewe