Density Functional Method Studies of XH (XC, N, O, Si, P, S) Bond Dissociation Energies

Abstract

AbstractThe performances of the density functional theory (DFT) methods in calculating XH bond dissociation energies (BDE, XC, N, O, Si, P, S) were evaluated. It was found that most DFT methods including B3LYP, B3PW91, G96LYP, PBE1PBE and BH&HLYP significantly underestimated the XH BDE by as much as 13–24 kJ/mol. The underestimation is not due to the use of finite basis set, because the DFT methods still significantly underestimate the XH BDE with the complete basis set. Therefore, these DFT methods can not be used to calculate the BDE directly. Nevertheless, the B3P86 method shows very small underestimation for the XH BDE. Further analysis suggests that there be no advantage for using the restricted open‐shell DFT methods. The unrestricted DFT methods actually perform slightly better than the restricted open‐shell DFT methods in most cases. Finally, it was found that the underestimation by the DFT methods was largely systematic. The use of the calibrated UDFT/6‐311++G(d, p) method was recommended to calculate the XH BDE.