ORCA.

About ORCA

ORCA is a general-purpose quantum chemistry package featuring a variety of methods including semi-empirical, density functional theory, many-body perturbation, coupled cluster, and multireference methods. ORCA provides an easy-to-learn input structure and thus high accessibility of quantum chemical approaches and workflows. The ORCA program package is mainly developed by Frank Neese, the department of molecular theory and spectroscopy at the Max-Planck-Institut für Kohlenforschung, and the FACCTs GmbH which also manages commercial licensing to industry. ORCA is generally freely available for academic use.