Basis set convergence in Hartree-Fock calculations of some diatomic molecules containing first and second-row atoms

Abstract

Investiga-se a convergência de conjuntos de bases em direção ao limite numérico da energia Hartree-Fock (HF) total para as seqüências hierárquicas dos conjuntos de bases XZP e ccpVXZ. Para as duas hierarquias, melhoramentos significativos são obtidos com cada incremento em X. Para estimar o limite do conjunto de base completo, uma forma exponencial foi usada. Entre as várias aproximações consideradas aqui, uma extrapolação exponencial de três parâmetros aplicada aos resultados TZP, QZP e 5ZP deu os limites do conjunto de bases mais precisos. Em adição, energias HF dos orbitais moleculares ocupados mais altos de algumas moléculas diatômicas foram calculadas com o conjunto 5ZP e comparadas com as correspondentes obtidas com o conjunto cc-pV5Z e com um método numérico HF.Basis set convergence towards the numerical limit of the total Hartree-Fock (HF) energy is investigated for the hierarchical sequences of the XZP and cc-pVXZ basis sets. For both hierarchies, solid improvements are obtained with each increment in X. To estimate the complete basis set limit, an exponential form was used. Among the various approaches considered here, a three-parameter exponential extrapolation applied to the TZP, QZP, and 5ZP results yields the most accurate basis set limits. In addition, 5ZP highest occupied molecular orbital HF energies of some diatomic molecules are evaluated and compared with the corresponding ones obtained with the cc-pV5Z and numerical HF results.

Gaussian basis set of double zeta quality for atoms K through Kr: Application in DFT calculations of molecular properties

“…At the HF, Möller‐Plesset second‐order (MP2), and DFT levels, these sets were applied with success in calculations of energies, dissociation energy, harmonic vibrational frequency, and electric dipole moment of a set of diatomic molecules containing atoms of the first‐ and second‐row11–13 and second‐row diatomic hydrides 14. In addition, for some diatomics, the CBS limits12, 15 of the HF and MP2 methods were examined with the hierarchical sequences of XZP and cc‐pVXZ basis sets. One verified that among the various schemes used to estimate the basis set limits, the extrapolated total HF and second order energies of the Jorge's hierarchy gave the best values.…”

Basis-set convergence of nuclear magnetic shielding constants in molecular HF and MP2 calculations

“…Recently, Jorge et al presented segmented contracted double [7], triple and quadruple [8] and quintuple [9] zeta valence quality plus polarization function (XZP, X = D, T, Q and 5, respectively) basis sets for the atoms from H to Ar and; at the HF, DFT and MP2 levels of theory, they were applied with success in calculations of energies, dissociation energy, bond length, harmonic vibrational frequency and electric dipole moment of a set of diatomic molecules containing atoms of the firstand second-row [7][8][9][10] and second-row diatomic hydrides [11]. Using the hierarchical sequence of XPZ [7][8][9] basis sets the complete basis-set (CBS) limit of total HF [12] and second-order correlation [9] energies were estimated and, then, compared, respectively, with numerical HF and MP2 with linear terms r 12 results.…”