Anchoring the Potential Energy Surface of an Important Atmospheric Van Der Waals Dimer, the H2o⋯o2 Complex

Abstract

The focus of this paper is the weakly-bound H2O⋯O2 van der Waals dimer. The global minimum has an electronic dissociation energy of 0.70kcalmol-1 at the spin unrestricted CCSD(T) level of theory (UCCSD(T)) in conjunction with a correlation consistent quadruple-zeta basis set augmented with diffuse functions on all heavy atoms, denoted haQZ (i.e., cc-pVQZ for H and aug-cc-pVQZ for O). Eleven other stationary points are also characterized at the UCCSD(T)/haQZ level of theory, all of which lie within 0.5kcalmol-1 of the global minimum and have at least one imaginary frequency (ni≥1). The spin unrestricted MP2 method (UMP2) yields very similar structures and energies for the twelve stationary points. However, the UMP2 vibrational frequencies provide a qualitatively different description of the potential energy surface (more than a single minimum), of the frequency shifts upon complexation and of the resulting infrared intensities of the complex. The UCCSD(T)/haQZ computations indicate only one of the twelve H2O⋯O2 structures is a minimum and that it exhibits appreciable infrared intensity for one of the lowest energy intermolecular vib rational modes, unlike the related H2O⋯N2 system.

Department(s)

Chemistry

Comments

National Science Foundation, Grant 1338056

Keywords and Phrases

Atmospheric van der Waals complexes; CCSD(T) CBS limit; Harmonic vibrational frequencies; Oxygen water dimer

International Standard Serial Number (ISSN)

2210-271X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 Elsevier, All rights reserved.

Publication Date

15 Nov 2015

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