Comparative study of errors in HeH- interaction energy calculations

摘要

Basis set truncation error (BSTE), size extensivity Error (SEE), zero point vibrational energy (ZPVE), and basis set superposition error (BSSE) of HeH- weak van der Waals interaction energy were determined and compared at the self-consistent field (SCF), many-body perturbation theory (MBPT), and coupled cluster (CC) methods using even-tempered functions. Isotope substitution effects and the role of bond function augmentation were taken into account. Apart from core correlation energy error (CCEE), which is absent from HeH- interaction energy, the results confirm that BSTE is the most important source of error, followed by SEE of the truncated configuration interaction (CI) expansion, ZPVE and BSSE in a descending order. introducing quadrable excitations to the truncated CI expansion reduces the magnitude of SEE by similar to 45.7%, and BSSE correction is not necessary even at the electron correlation level. While bond function augmentation reduces BSSE at the Hartree-Fock, it has an oscillating behavior at the electron correlation level. (C) 1998 John Wiley & Sons, Inc. [References: 71]