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

Abstract

Sequences of increasing size atom centered basis sets of Gaussian-type functions for the ground state of the CS molecule are generated with the molecular improved generator coordinate Hartree-Fock (HF) method. At the HF level, total and orbital energies and electric dipole moment and, at the second-order Mφller-Plesset (MP2) level, correlation and dissociation energies and electric dipole moment were calculated and compared with the results obtained with other Gaussian basis sets reported in the literature. Considering our largest basis set, the HF energy is in error by 56.2 µhartree and the second order correlation energy corresponds to ∼ 80% of an estimate of the limiting value. At the MP2 level, the dipole moment and the dissociation energy computed with our largest basis set are in good agreement with the corresponding experimental values. The CS molecule is considered a prototype for systems containing atoms from different rows of the periodic table.

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.…”

“…Table displays the theoretical total Hartree–Fock (HF) energies obtained with contracted hybrid‐basis set (this work); contracted atom‐optimized basis sets (ADZP and aug‐cc‐pVDZ); and uncontracted molecule‐optimized basis sets . Numerical HF (NHF) results are also shown.…”

“…The molecular GCHF (MGCHF) and the molecular improved GCHF (MIGCHF) methods, which use the linear combination of atomic orbitals (LCAO) structure, have been used to generate molecule‐optimized basis sets. In previous papers, the MIGCHF method has been successfully applied to generate accurate basis sets, using atom‐centered basis sets of primitive Gaussian‐type functions for some diatomic and triatomic systems …”