The DIRAC code for relativistic molecular calculations
Trond Saue, Radovan Bast, André Severo Pereira Gomes, Hans Jørgen Aa. Jensen, Lucas Visscher, I. Agustín Aucar, Di Remigio, Roberto, Kenneth G. Dyall, Ephraim Eliav, Elke Faßhauer, Timo Fleig, Loïc Halbert, Erik D. 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 1-, 2- and 4-component relativistic molecular calculations at the level of Hartree--Fock, Kohn--Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, coupled cluster and electron propagator 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 the inclusion of environmental effects through three different classes of increasingly sophisticated embedding approaches: the implicit solvation polarizable continuum model, the explicit polarizable embedding, and frozen density embedding models. DIRAC was one of the earliest codes for relativistic molecular calculations and remains a reference in its field.