The infrared spectrum of cyclotetraoxygen, O4: A theoretical investigation employing the single and double excitation coupled cluster method

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Abstract
Cyclotetraoxygen is hypothesized to be a substance of high energy density. In order to aid in the identification of this molecule, its structure and infrared spectrum have been predicted using the coupled cluster single and double excitation (CCSD) method. At this level of theory, the bond length is predicted to be 1.473 Å and the O–O–O–O torsional angle is 27°. The heat of formation is estimated to be 83 kcal/mol; thus O4 is predicted on a per atom basis to lie 21 kcal/mol above two separated O2 molecules. The full quartic force field was determined from theory and an anharmonic prediction of the infrared‐active fundamentals places them close to 815 and 724 cm−1.