The relativistic effect on energies of light elements: a RESC-BOP study

The scalar relativistic contribution to energies and geometries of molecule s containing the first- and second-row atoms is estimated by the density fu nctional theory with the BOP functional. The relativistic effect is conside red through the relativistic scheme by eliminating small-component (RESC) o f the four-component Dirac equation. The relativistic corrections to the en ergies of light elements are rather small but show a clear-cut trend. The s calar relativistic effect nearly always reduces atomization energies, ioniz ation potentials, and electron affinities. Furthermore, the relativistic co rrections to the ionization potentials and electron affinities increase wit h the atomic numbers in the component atoms. On the other hand, there is li ttle change in the geometric parameters of the first- and second-row diatom ic molecules. (C) 2001 Elsevier Science B.V. All rights reserved.