autoCAS: A Program for Fully Automated Multiconfigurational Calculations

We present our implementation autoCAS for fully automated multiconfigurational calculations, which we also make available free of charge on our webpages. The graphical user interface of autoCAS connects a general electronic structure program with a density‐matrix renormalization group program to carry out our recently introduced automated active space selection protocol for multiconfigurational calculations (Stein and Reiher, J. Chem. Theory Comput., 2016, 12, 1760). Next to this active space selection, autoCAS carries out several steps of multiconfigurational calculations so that only a minimal input is required to start them, comparable to that of a standard Kohn–Sham density‐functional theory calculation, so that black‐box multiconfigurational calculations become feasible. Furthermore, we introduce a new extension to the selection algorithm that facilitates automated selections for molecules with large valence orbital spaces consisting of several hundred orbitals. © 2019 Wiley Periodicals, Inc. autoCAS program for fully automated multiconfigurational calculations is presented. The program requires a minimal input, comparable to that of a density‐functional theory calculation and automatically selects an appropriate active space based on orbital entanglement entropies calculated from a partially converged density‐matrix renormalization group calculation. Hence, autoCAS turns multiconfigurational calculations into a black‐box method. It is implemented as a graphical user interface and is part of the SCINE project for chemical interaction networks.