A NEW ECP BASIS SET FOR ACCURATE CALCULATIONS OF DYNAMIC RAMAN INTENSITIES

Resumo

Polarized Gaussian basis sets adapted to effective core potentials (ECPs) for ab initio calculations of frequency dependent Raman intensities are presented. The method of electric polarization of Gaussian basis functions developed by Sadlej is applied to the small-size pseudopotential basis sets SBKJC and Stuttgart’s ECPnMWB to generate new basis sets, named as pSBKJC and pStuttgart, which are appropriate for calculation of dynamic polarizability and Raman cross sections. The Raman scattering activities of alkali earth hydrides (MH₂, M=Be to Ba) and for chalcogenides (H₂X, X=O to Po) were evaluated at the excitation frequency of 632.8 nm using these new basis sets and the all-electron basis set Sadlej-pVTZ. These calculations were performed at the non-relativistic time-dependent Hartree-Fock (TDHF) level and also with its relativistic counterparts, the Dirac-Hartree-Fock/Spin-Free (DHF/SF) (no spin-orbit coupling) and Dirac-Hartree-Fock (DHF) levels. Due to the use of relativistic ECPs, Hartree-Fock calculations using these new basis sets can also recover most of the relativistic effects appearing in the Raman intensities. The overall agreement between the HF/pSBKJC and HF/Sadlej-pVTZ Raman scattering activities is 8.6% while the comparison of HF/pStuttgart with HF/Sadlej-pVTZ data shows a better agreement of 5.3%.