A general toolbox for the calculation of higher-order molecular properties using SCF wave functions at the one-, two- and four-component levels of theory

We outline a new approach for the calculation of higher-order molecular properties for self-consistent field (SCF) wave functions (or Kohn-Sham density-functional theory) expressed in time- and perturbation-dependent basis sets. The approach is based on an atomic-orbital-based, open-ended quasienergy derivative formalism, and is applicable for use in linear scaling SCF calculations. In order to enable the calculation of any response property, we have also developed open- ended one- and two-electron integral derivative programs, as well as a program that can calculate derivatives of exchange- correlation functionals to any order using automatic differentiation. These modules have been interfaced to both the Dalton and DIRAC programs. This allows us to calculate molecular properties at the one-, two- and four-component levels of theory using a common theoretical framework and code. © 2012 American Institute of Physics.