Systematic Errors in ab Initio Bond Dissociation Energies

Published

August 1, 1998

Author(s)

Karl K. Irikura

Abstract

Bond dissociation energies (D_o) for 41 small molecules were calculated at 19 levels of ab initio theory up to CCSD(T)/cc-pVTZ, using geometries and vibrational zero-point energies from B3LYP/6-31G* hybrid density-functional calculations. Empirical correlations between the errors in the ab initio bond strengths and the following quantities were examined: (1) the distance between the bonded atoms, (2) the electron density at the mid-bond critical point, and (3) the contribution of dynamic electron correlation to the bond strength. Correlation 1 is related to the BAC-MP4 method of Melius and co-workers, and correlation 3 corresponds to the SAC methods of Truhlar, Gordon, and co-workers and to the PCI methods of Siegbahn, Blomberg, and co-workers. For each type of empirical correction, empirical estimates of the standard uncertainty for an arbitrary prediction are also provided. Type 3 correlations fail for bonds involving second-row elements (e.g., silicon), suggesting that the cc-pVTZ basis sets are not correlation balanced across the different periods. For the lighter elements, however, all three corrections are effective and could be refined into prescriptive methods.

Citation

Journal of Physical Chemistry A

Volume

102

Issue

No. 45

Pub Type

Journals

Keywords

ab initio, bond dissociation energy, bond energy, density functional, empirical correction, thermochemistry

Citation

Irikura, K. (1998), Systematic Errors in ab Initio Bond Dissociation Energies, Journal of Physical Chemistry A (Accessed April 19, 2024)