Ab initio relativistic quantum chemistry:: four-components good, two-components bad!

In view of the debate which resulted from the introductory lecture at this meeting, this article has been submitted to address the issues raised concerning the validity and implementation of relativistic theories of many-electron systems. We present the formulation and construction of BERTHA, our relativistic molecular structure program, and illustrate features of relativistic electronic structure theory with examples. These include magnetic and hyperfine interactions in small molecules, the use of spinor basis functions which include a dependence on a magnetic field strength, NMR shielding constants, P-odd interactions in chiral molecules, and computational details of a relativistic ab initio treatment of germanocene. © 1999 Academic Press Inc.