A comparison of scalar-relativistic ZORA and DKH density functional schemes: monohydrides, monooxides and monofluorides of La, Lu, Ac and Lr

The zeroth-order regular approximation (ZORA) to the Dirac Hamiltonian and the Douglas-Kroll-Hess Hamiltonian (DKH) in their scalar-relativistic formu lation have been implemented in a density functional code. The two approach es are compared on the same footing, i.e., using the same exchange-correlat ion functionals, basis sets and grids for numerical integration. The monohy drides, monooxides and monofluorides of La, Lu, Ac and Lr have been selecte d for a calibration study. Both methods yield very consistent results for b ond lengths, binding energies and vibrational constants. Comparison is also made to experimental data as well as other relativistic all-electron and p seudopotential results. (C) 2001 Elsevier Science B.V. All rights reserved.