MULTICONFIGURATIONAL SELF-CONSISTENT-FIELD CALCULATIONS OF NUCLEAR SHIELDINGS USING LONDON ATOMIC ORBITALS

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 (H2O, H2S, CH4, N-2, CO, HF F-2, and SO2) 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.