The Far-Infrared Spectrum of Methoxymethanol (CH-O-CHOH): A Theoretical Study.

Methoxymethanol (CHOCHOH), an oxygenated volatile organic compound of low stability detected in the interstellar medium, represents an example of nonrigid organic molecules showing various interacting and inseparable large-amplitude motions. The species discloses a relevant coupling among torsional modes, strong enough to prevent complete assignments using effective Hamiltonians of reduced dimensionality. Theoretical models for rotational spectroscopy can improve if they treat three vibrational coordinates together.

Theoretical structural and spectroscopic characterization of peroxyacetic acid (CH-CO-OOH): study of the far infrared region.

Peroxyacetic acid, a non-rigid oxygenated organic molecule which acts in the atmosphere as a reservoir of HO and RO radicals, is studied using highly correlated methods with the aim of its spectroscopic characterization in the gas phase. The study focuses on the far infrared region providing reliable rovibrational parameters such as energy levels and splittings. The molecule presents three conformers that inter-convert by internal rotation, drawing a potential energy surface of 12 minima.

Rotational excitation of CH anion in collision with H.

The discovery of anions in the interstellar medium has shown that they are very reactive species. This gave them great importance in the modeling of the chemical and astrophysical evolution of the interstellar medium. The detection of the first anion CH followed by the other anions CH, CH and CN in the interstellar medium has encouraged research on other detectable anions.

Rotational excitation of C(XΣ ) by - and -H.

A new four dimensional (4D) potential energy surface for the C(XΣ )-H van der Waals system is generated. The potential was obtained from a multi-reference internally contracted configuration-interaction method including the Davidson correction (MRCI+Q). The four atoms were described using the augmented correlation-consistent quadruple zeta (aug-cc-pVQZ) basis sets.

Dynamics of AlOH inelastic scattering with p-H(J = 0) on a full and accurate potential energy surface.

Alkali aluminum hydroxide, AlOH, has associated features with the chemistry of aluminum-bearing species and generally with metal hydroxide molecules in the interstellar clouds where it has been observed. The aim of this work is to obtain accurate rotational rate coefficients of AlOH colliding with the most abundant molecular species in the interstellar medium (ISM), H2, in its lowest rotational state p-H2(J = 0) for the kinetic temperature range 5-80 K. A full and accurate 4D-PES was generated using explicitly correlated coupled cluster with single, double and perturbative triple excitation CCSD(T)-F12a augmented by the aVTZ basis set.

Inelastic scattering dynamics of ortho and para hydronium ions, o-HO and p-HO, with He at low temperature.

The hydronium ion, H3O+, presents a crucial key to understanding the chemistry of the interstellar clouds where it has been frequently observed. The present paper is devoted to studying the inelastic scattering of both forms of the hydronium ion, o-H3O+ and p-H3O+, by helium atoms. The interaction potential between H3O+ and He was mapped in Jacobi coordinates leading to a new three dimensional potential energy surface (3D-PES) at the CCSD(T)/aug-cc-pVQZ+BF (CCSD(T)/AVQZ+BF) level of theory.