title: Precise equilibrium structure determination of hydrazoic acid (HN3) by millimeter-wave spectroscopy.
abstract: The millimeter-wave spectrum of hydrazoic acid (HN3) was analyzed in the frequency region of 235-450 GHz. Transitions from a total of 14 isotopologues were observed and fit using the A-reduced or S-reduced Hamiltonian. Coupled-cluster calculations were performed to obtain a theoretical geometry, as well as rotation-vibration interaction corrections. These calculated vibration-rotation correction terms were applied to the experimental rotational constants to obtain mixed theoretical/experimental equilibrium rotational constants (Ae, Be, and Ce). These equilibrium rotational constants were then used to obtain an equilibrium (Re) structure using a least-squares fitting routine. The Re structural parameters are consistent with a previously published Rs structure, largely falling within the uncertainty limits of that Rs structure. The present Re geometric parameters of HN3 are determined with exceptionally high accuracy, as a consequence of the large number of isotopologues measured experimentally and the sophisticated (coupled-cluster theoretical treatment (CCSD(T))/ANO2) of the vibration-rotation interactions. The Re structure exhibits remarkable agreement with the CCSD(T)/cc-pCV5Z predicted structure, validating both the accuracy of the ab initio method and the claimed uncertainties of the theoretical/experimental structure determination.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Brent K
authors.initials: BK
authors.lastname: Amberger
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Esselman
authors.affiliation: Institute for Theoretical Chemistry, Department of Chemistry, The University of Texas-Austin, Austin, Texas 78712, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Stanton
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: R Claude
authors.initials: RC
authors.lastname: Woods
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McMahon