The DIRAC code for relativistic molecular calculations
Trond Saue, Radovan Bast, André Severo Pereira Gomes, Hans Jørgen Aa. Jensen, Lucas Visscher, Ignacio Agustín Aucar, Roberto Di Remigio, Kenneth G. Dyall, Ephraim Eliav, Elke Fasshauer, Timo Fleig, Loïc Halbert, Erik Donovan Hedegård, Benjamin Helmich-Paris, Miroslav Iliaš, Christoph R. Jacob, Stefan Knecht, Jon K. Laerdahl, Marta L. Vidal, Malaya K. Nayak, Małgorzata Olejniczak, Jógvan Magnus Haugaard Olsen, Markus Pernpointner, Bruno Senjean, Avijit Shee, Ayaki Sunaga, Joost N. P. van Stralen
Abstract
DIRAC is a freely distributed general-purpose program system for one-, two-, and four-component relativistic molecular calculations at the level of Hartree-Fock, Kohn-Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, electron propagator, and various flavors of coupled cluster theory. At the self-consistent-field level, a highly original scheme, based on quaternion algebra, is implemented for the treatment of both spatial and time reversal symmetry. DIRAC features a very general module for the calculation of molecular properties that to a large extent may be defined by the user and further analyzed through a powerful visualization module. It allows for the inclusion of environmental effects through three different classes of increasingly sophisticated embedding approaches: the implicit solvation polarizable continuum model, the explicit polarizable embedding model, and the frozen density embedding model.