The original article to which this Erratum refers was published in International Journal of Quantum Chemistry (2004) 100(6) 1170–1178.

No abstract

Electronic structures and chemical bonding within the NdO and UOmolecules have been studied computationally via the QR-SCMEH-MO (quasirelativistic-self-consistent modified extended Hückel-molecular orbital) method. This is a non-ab initio, self-consistent, nonempirical routine that accounts for correlation in an approximate way. It also incorporates other features so as to account for all electron interactions. Both molecules were found to be bonding [contrary to a report based on ab initio density functional theory (DFT)-SCF relativistic calculations on UO]. The covalency in UO is somewhat greater than that of NdO, which for all practical purposes is mostly electrostatic. Good agreement between calculated and observed bond dissociation energies and ionization potentials have been obtained. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 90: 629-633, 2002

At the 2001 Sanibel Symposium a presentation of MO calculationsderived from the QR-SCMEH-MO method applied to Cr 2 and Mo 2 was made and subsequently published in the proceedings [22]. This was followed by similar unpublished calculations on W 2 and Sg 2 presented at the 43rd Sanibel Symposium in 2003. Unfortunately, in neither of these instances were specific evaluations regarding magnitudes of spin-pairing energies versus MO eigenvalues taken into account. However, when these factors were subsequently examined in detail, we found that the pattern of MO occupancies and overall bonding features were significantly altered from that reported previously. Among these M 2 molecules (Cr 2 and Mo 2 ) are found to have open-shell, triplet delta HOMOs, in which the spins are antiferromagnetically coupled to produce spin singlet ground states. It has been observed that the electronic structures of these molecules must be ascribed apparently to correlation effects confined not only to the valence electrons, but to valence/valence-core electrons as well. Within a transition metal series the atomic configurations are: ns 2 np 6 nd a (n ϩ 1)s b ; 1 Յ a Յ 10; 1 Յ b Յ 2. The nd a (n ϩ 1)s b portion is naturally the valence component, and the ns 2 np 6 portion is the valence-core component. All levels below the latter are the inner core, which are frozen in these calculations. Consequently, in molecular bonding there is not only valence correlation, but the likelihood of valence/valence-core correlation as well; particularly since these are no longer necessarily correlated as they were in the separated atoms. There apparently are no influences from the inner core. Of course, these features apply specifically to the SCMEH-MO method. Because the SCMEH-MO method, in general, is not an ab initio type of routine, wherein all electron correlation is explicitly accounted for, it is essential to limit correlation only to those AOs specifically affected by bonding. Furthermore, these effects seem to be uniquely associated with the

ABSTRACT:In this study, the correlation between open-shell valence and closedshell valence-core electrons is shown to be significant, with regard to an adequate description of the bonding in transition metal diatomic molecules. The SCMEH-MO (self-consistent modified extended Huckel molecular orbital) method is well suited for partitioning these two influences, in terms of their independent and collective effects on the electrons within the occupied mo-s. Two test cases, Cr 2 and Mo 2 are presented to demonstrate the nature and magnitude of these valence/valence-core interactions.