Multiconfigurational self-consistent field calculations of nuclear shieldings using London atomic orbitals

Abstract

Articles you may be interested inPolarized atomic orbitals for self-consistent field electronic structure calculations Nuclear shielding calculations are presented for multiconfigurational self-consistent field wave functions using London atomic orbitals (gauge invariant atomic orbitals). Calculations of nuclear shieldings for eight molecules (H 2 0, H 2 S, CH 4 , N 2 , CO, HF, F 2 , and S02) are presented and compared to corresponding individual gauges for localIzed orbitals (IGLO) results. The London results show better basis set convergence than IGLO, especially for heavier atoms. It is shown that the choice of active space is crucial for determination of accurate nuclear shielding constants.8178

GIAO-DFT prediction of accurate NMR parameters in selected glucose derivatives

“…28 The recent efficient implementation 19 of the GIAO method for predicting NMR properties has been successfully used in the calculation of proton chemical shift anisotropy in (H 2 O) 17 clusters. 20 Further, the use of London orbitals (GIAO method) was recently recommended by Ruud and Helgaker 21 because it provides better convergence of NMR parameters for non-hydrogen elements.…”

Magnetic Shielding Studies of C2 and C2H2 Support Higher than Triple Bond Multiplicity in C2

“…The offnucleus shielding tensors required for the contour plots were calculated using full-valence ground-state complete-active-space self-consistent field (CASSCF) wavefunctions constructed from gauge-including atomic orbitals (GIAOs), with '8 electrons in 8 orbitals' for C 2 , and '10 electrons in 10 orbitals' for C 2 H 2 , in the standard cc-pVQZ basis set. All CASSCF-GIAO calculations were carried out using the MCSCF-GIAO (multiconfigurational SCF with GIAOs) methodology described in references [15,16] and implemented in the Dalton program package. [17] For comparison purposes, similar contour plots for the total electron density, .r/, in C 2 and C 2 H 2 , were drawn from the respective CASSCF (8,8)/cc-pVQZ and CASSCF(10,10)/cc-pVQZ data obtained using GAUSSIAN09.…”

Solvent effects on the NMR parameters of H2S and HCN

“…The results have metries, and one orbital of A symmetry, and has 2 previously been used for gas-phase investigations of nuclear shieldings. 16 For HCN, we have used the active space of ref. 33, which consists of five orbitals of A symmetry, and two of B and B 1 1 2 symmetries.…”