Gaussian, complete basis set, and density functional theory methods evaluation of the electron affinity for BO, B, and O B.S. Jursic * Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA Received 4 August 1998; accepted 14 August 1998 Abstract The electron affinities for boron, oxygen and BO were computed with highly reliable Gaussian and complete basis set ab initio methods, as well as with several density functional theory methods. There is a general agreement between ab initio and B3LYP hybrid DFT methods that the electron affinity for BO should be between 2.5 and 2.6 eV; possibly 2.55 eV as computed by the CBSQ ab initio method. This value is substantially lower than the experimentally determined finding, therefore, a revision of the experimental electron affinity for BO is suggested. The B–O bond dissociation energies for neutral and anionic BO was also estimated. Good agreement between Gaussian, CBS and hybrid B3LYP DFT values were obtained, suggesting that computed values are accurate and the hybrid DFT method is reliable for performing this computational study. On the contrary, local spin density approximation generates energies that are substantially higher and should be avoided when a computational study of this and similar chemical systems are considered.  1999 Elsevier Science B.V. All rights reserved. Keywords: Electron affinity; Boron; Boron–oxide; Complete basis set ab initio; DFT 1. Introduction Knowing accurate values for bond dissociation energies as well as electron affinity is very important when explaining experimental kinetic data [1–3]. Theoretical chemists have developed computational methods that can accurately compute these properties. We have used both highly accurate ab initio as well density functional theory methods to evaluate electron affinity [4–7] and bond dissociation energies [8–14]. Highly accurate ab initio methods, such as Gaussian (G1, G2 and G2MP2) and quadratic complete basis set (CBSQ) are regarded as being reliable for computing these two physical properties of chemical systems [15]. In many cases, computational chemists use elec- tron affinity as a starting point for the evaluation of the accuracy of computational methods. One such chemi- cal system that requires special attention is the experi- mental value for the electron affinity of BO. It is difficult to reproduce the electron affinity; therefore, it is normal that this problem would attract the wide- spread interest of computational chemists [16–20]. There are at least two experimental values reported for the electron affinity of BO, by Jensen in 1970 [21] and Srivastava and coworkers in 1971 [22]. The values differ substantially, ranging from 3.50 to 3.12 eV. Computational methods predict the electron affinity to be between 2.27 and 2.79 eV. Ab initio computational studies currently performed by Schaefer and Rienstra [20] with the CCSD(T) suggest a value of 2.57 eV for the electron affinity of BO. In an attempt to finally resolve the dispute over the electron affinity for BO, we have performed highly accurate ab Journal of Molecular Structure (Theochem) 467 (1999) 1–6 0166-1280/99/$ - see front matter  1999 Elsevier Science B.V. All rights reserved. PII: S0166-1280(98)00378-9 * Tel.: + 1-504-280-7090; fax: + 1-504-280-6860. E-mail address: bsjcm@uno.edu (B.S. Jursic)