The COLUMBUS program system provides the tools for performing high-level multireference (MR) computations, including the multireference configuration interaction (MRCI) method and its multireference averaged quadratic coupled cluster (MR-AQCC) extension, allowing computations on a wide range of fascinating atomic and molecular systems, including the treatment of open-shells and complicated excited state phenomena. The inclusion of spin-orbit coupling (SOC) directly within the MRCI step enables the description of systems containing heavy elements, such as lanthanides and actinides, whose properties are strongly influenced by SOC. Analytic energy gradients and nonadiabatic couplings at the correlated MRCI level provide the foundation for a variety of dynamics studies, giving insight into ultrafast photochemistry. New and ongoing method developments in COLUMBUS include the computation of spin densities, improved descriptions of ionic states, enhancements to the AQCC method, and the porting of COLUMBUS to graphical processing units (GPUs). New external interfaces enable an enhanced description of electronic resonances and molecules in strong laser fields. This work highlights these new developments while providing a detailed account of the diverse applications of COLUMBUS in recent years.

Advanced Scientific Computing and Modeling Laboratory Aeronautics Institute of Technology 12228 900 São José dos Campos Brazil

Aix Marseille University CNRS ICR 13397 Marseille France

Chemical Sciences and Engineering Division Argonne National Laboratory Lemont Illinois 60439 United States

Chemistry Department and Institute of Soft Matter Georgetown University Washington District of Columbia 20057 1227 United States

Computational Science Division Argonne National Laboratory 9700 South Cass Avenue Lemont Illinois 60439 United States

Departamento de Física Instituto Tecnológico de Aeronáutica 12228 900 São José dos Campos São Paulo Brazil

Departamento de Química CCEN Universidade Federal da Paraíba 58059 900 João Pessoa Brazil

Department of Chemistry Aeronautics Institute of Technology 12228 900 São José dos Campos Brazil

Department of Chemistry and Biochemistry Texas Tech University Lubbock Texas 79409 United States

Department of Chemistry and Biochemistry The Ohio State University Columbus Ohio 43210 United States

Department of Chemistry Gottwald Center for the Sciences University of Richmond Richmond Virginia 23173 United States

Department of Chemistry Loughborough University Loughborough LE11 3TU United Kingdom

Department of Chemistry Northwestern University Evanston Illinois 60208 United States

Department of Chemistry Temple University 1901 N 13th St Philadelphia Pennsylvania 19122 United States

Department of Chemistry University at Buffalo State University of New York Buffalo New York 14260 3000 United States

Department of Mechanical Engineering Texas Tech University Lubbock Texas 79409 United States

Department of Physics Ludwig Maximilian University Theresienstrasse 37 80333 Munich Germany

Faculty of Chemistry Nicolaus Copernicus University in Torun 87100 Torun Poland

Institut Universitaire de France 75231 Paris France

Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic CZ 16610 Prague Czech Republic

Institute of Theoretical Chemistry Faculty of Chemistry University of Vienna 1090 Vienna Austria

IT4Innovations VŠBTechnical University of Ostrava 708 00 Ostrava Czech Republic

J Heyrovsky Institute of Physical Chemistry Academy of Sciences of the Czech Republic v v i Dolejškova 3 18223 Praha 8 Czech Republic

Laboratoy of Theoretical Chemistry Institute of Chemistry ELTE Eötvös Loránd University H 1117 Budapest Hungary

Mulliken Center for Theoretical Chemistry University of Bonn 53115 Bonn Germany

National Renewable Energy Laboratory 15013 Denver West Parkway Golden Colorado 80401 United States

Physical Sciences and Computational Division Pacific Northwest National Laboratory Richland Washington 99354 United States

ScaDS AI Dresden Leipzig 04105 Leipzig Germany

Stanford Research Computing Stanford University Stanford California 94305 United States

Vienna Research Platform on Accelerating Photoreaction Discovery University of Vienna 1090 Vienna Austria

Wilhelm Ostwald Institute for Physical and Theoretical Chemistry Leipzig University 04103 Leipzig Germany

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