Ryan C. Fortenberry

ArH2+ and NeH2+ as global minima in the Ar+/Ne+ + H2 reactions: energetic, spectroscopic, and structural data

In light of the recent discovery of ArH+ in the Crab nebula, it is shown through high-level quantum chemical comptuations that the global minima on the Ar+/Ne+ + H2 potential energy surfaces are ArH2+ and NeH2+. Hence, ArH2+ may be a necessary intermediate in the Ar+ + H2 -> ArH+ + H formation reaction proposed in the same work where ArH+ is first reported in the Crab nebula. ArH2+ is also probably an intermediate in the alternative Ar + H+2 -> ArH+ + H reaction. Additionally, it is shown that Ne+ + H2 -> NeH+2 will subsequently most likely yield Ne + H+2 and not NeH+ + H offering a possible rationale as to the absence of NeH+ in spectra obtained from the interstellar medium (ISM). Following from this, spectroscopic data (both rotational and vibrational) are provided for NeH2+ and ArH2+ through the use of highly-accurate quantum chemical quartic and cubic force fields. All possible isotopologues are also included for 20Ne, 22Ne, 36Ar, 38Ar, 40Ar, 1H, and D. The dipole moments for these systems are quite large at 5.61 D for NeH2+ and 4.37 D for ArH2+. The spectroscopic constants provided will aid in the potential detection of these open-shell noble gas dihydride cations in the ISM.

Interstellar Anions: The Role of Quantum Chemistry

Six anions have been conclusively detected in the interstellar medium (ISM). They all arrived within a five-year window ending five years ago. Why have no new anions been detected? It is likely a lack of laboratory data for novel anions. This work reviews the role that valence and dipole-bound excited states may play in the formation, detection, and lifetime of anions that may yet be observed in the ISM and how quantum chemistry enhances this understanding. The list of interstellar anions has certainly not been exhausted by any means, but electronic, spectroscopic, and structural data must be provided to aid in any future detections. Quantum chemistry has the flexibility and completeness to provide a full picture of these systems and has shown exceptional accuracies of late. The work reviewed herein gives an overview of what quantum chemical computations have produced and will continue to provide related to anions and how this will enhance both laboratory experiment and astronomical observation.

Quartic force field-derived vibrational frequencies and spectroscopic constants for the isomeric pair SNO and OSN and isotopologues

The SNO and OSN radical isomers are likely to be of significance in atmospheric and astrochemistry, but very little is known about their gas phase spectroscopic properties. State-of-the-art ab initio composite quartic force fields are employed to analyze the rovibrational features for both systems. Comparison to condensed-phase experimental data for SNO has shown that the 1566.4 cm(-1) ν1 N-O stretch is indeed exceptionally bright and likely located in this vicinity for subsequent gas phase experimental analysis. The OSN ν1 at 1209.4 cm(-1) is better described as the antisymmetric stretch in this molecule and is also quite bright. The full vibrational, rotational, and rovibrational data are provided for SNO and OSN and their single (15)N, (18)O, and (34)S isotopic substitutions in order to give a more complete picture as to the chemical physics of these molecules.

Additional diffuse functions in basis sets for dipole-bound excited states of anions

The existence of dipole-bound excited states has largely been shown by previous computation through the use of the standard LCAO-MO creation with numerous and diffuse atom-centered functions. Earlier work has suggested that the standard aug-cc-pVDZ basis set augmented with a small set of diffuse Rydberg-like orbitals is sufficient for the computation of dipole-bound ground states in anions. In this work, we explore the addition of four, even-tempered s-type functions augmenting the aug-cc-pVDZ set for the computation of dipole-bound excited states. It is shown herein that the inclusion of these orbitals is more cost-effective and internally accurate than atom-centered functions. Both vertical and adiabatic excitation energies are negligibly affected by the centering location of these additional diffuse functions. However, the excited state harmonic vibrational frequencies can be influenced by the placement of these additional diffuse functions, especially for the lowest energy modes.

Electronic and rovibrational quantum chemical analysis of C3P−: the next interstellar anion?

C

The performance of low-cost commercial cloud computing as an alternative in computational chemistry

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Energetics, structure, and rovibrational spectroscopic properties of the sulfurous anions SNO− and OSN−

P

QUANTUM CHEMICAL ROVIBRATIONAL DATA FOR THE INTERSTELLAR DETECTION OF c-C3H–

^-

TOWARD THE ASTRONOMICAL DETECTION OF THE PROTON-BOUND COMPLEX NN–HCO+: IMPLICATIONS FOR THE SPECTRA OF PROTOPLANETARY DISKS

is analogous to the known interstellar anion C

Methylidyne-replaced boron nitride fullerenes and nanotubes: a wave function study

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