1.1. About ORCA

ORCA[1] is a general-purpose quantum chemistry package initiated by Frank Neese in 1999 while finishing a postdoc at Stanford University. The name ORCA was inspired by a whale watching cruise of Frank Neese at the California coast and stands for itself and the association which comes with it.

ORCA is free for academic use and features a variety of quantum chemical methods including semi-empirical, density functional theory, many-body perturbation, coupled cluster, and multireference methods.

It is mainly developed by the research groups of 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 also benefits from a worldwide network of external developers and contributors.

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[1]

… so why is it called ORCA ? Frank Neese made the decision to write a quantum chemistry program in the summer of 1999 while finishing a postdoc at Stanford University. While thinking about a name for the program he wanted to write he decided against having yet another “whatever-Mol-something”. The name needed to be short and signify something strong yet elegant. During this time in the US Frank went on a whale watching cruise at the California coast—the name “ORCA” stuck. It is often asked whether ORCA is an acronym and over the years, various people made suggestions what acronym this could possibly be. At the end of the day it just isn’t an acronym which stands for anything. It stands for itself and the association which comes with it.