Highly accurate Gaussian basis sets for some 14‐electron diatomic systems*

Abstract

A molecular improved generator coordinate Hartree-Fock (HF) method is used to generate highly accurate Gaussian basis sets for N 2 , BF, CO, NO + , and CN − . For these molecular systems, sequences of basis sets of atom-centred Gaussian-type functions are employed to explore the accuracy achieved with this method. Our ground state HF total energies are lower than the corresponding ones calculated with other basis sets of primitive Gaussian-type functions reported in the literature. For the molecular systems here studied, the differences between the HF total energy results obtained with our largest basis sets and with a numerical HF method are equals to 38.2, 13.9, 33.0, 76.7, and 55.7 µhartree for N 2 , BF, CO, NO + , and CN − , respectively. We have also calculated the multipole electric moments and compare them with the corresponding experimental values and with results computed by other approaches.

Molecule‐adapted basis sets optimized with a quantum Monte Carlo method

“…In the initialization of the optimization procedure, we used the ADZP basis set to build the approximate wave functions corresponding to the ground states of H 2 O, CN − , N 2 , CO, BF, NO + , CO 2 , and CS systems, in their experimental geometries: nuclear distances = 0.9572 Å (H 2 O), 1.172 Å (CN − ), 1.094 Å (N 2 ), 1.1282 Å (CO), 1.2626 Å (BF), 1.063 Å (NO + ), 1.1600 Å (CO 2 ), 1.5344 Å (CS); bond angles = 104.52° (H 2 O), 180° (CO 2 ).…”

“…spd:spd bc n = 10 even‐tempered universal basis sets (atom‐centered plus bond‐centered sets) : N 2 (20s10p10d:20s10p9d bc ); CO (20s10p10d:20s10p9d bc ); BF (20s10p10d:20s10p10d bc ); NO + (20s10p10d:20s10p9d bc ); ii. basis sets optimized with the MIGCHF method: H 2 O, O(24s14p8d) H(22s9p); CN − , C(26s15p8d) N(26s15p8d); CO 2 , C(24s16p8d) O(24s16p6d); CS, C(24s14p7d) O(29s18p7d) …”

“…Results obtained from contracted hybrid‐basis set (this work), contracted atom‐optimized basis sets (ADZP and aug‐cc‐pVDZ, and experimental results (equilibrium geometries) are displayed in Table . The MAD/SD, in Å, of optimized bond lengths relatively to the experimental results are 0.010/0.006 for the hybrid‐basis set, 0.028/0.011 for aug‐cc‐pVDZ and 0.029/0.010 for ADZP.…”

Accurate Gaussian basis sets for the ground state of the CS molecule

“…Recently, Jorge et al [28] extended the IGCHF method for molecular systems and it was called molecular IGCHF (MIGCHF) method. Previous paper [29] examined the accuracy with which ground state HF energies of diatomic molecules containing first-row atoms can be calculated with the MIGCHF method by using atom centered basis sets of primitive Gaussian-type functions (GTFs). In Ref.…”

“…In Ref. [29], it was shown that accuracy smaller than 77 µhartree can be achieved for the total HF energies of fourteen electron diatomic systems. When a molecule contains atoms from different rows of the periodic table the importance of using a balanced basis set has been recognized for many years [30].…”