<i>e</i> <i>T</i> 2.0: An efficient open-source molecular electronic structure program

The eT program is an open-source electronic structure program with an emphasis on performance and modularity. As its name suggests, the program features extensive coupled cluster capabilities, performing well compared to other electronic structure programs and, in some cases, outperforming commercial alternatives. However, eT is more than a coupled cluster program; other models based on wave function theory (such as full and reduced-space configuration interaction and a variety of self-consistent field models) and density functional theory are supported. The second major release of the program, eT 2.0, has specialized functionality for strong light–matter coupling conditions. In addition, it includes a wide range of optimizations and algorithmic improvements, as well as new capabilities for exploring potential energy surfaces and for modeling experiments in the ultraviolet and X-ray regimes. Molecular gradients are now available at the coupled cluster level, and high-accuracy spectroscopic simulations are available at reduced computational cost within the multilevel coupled cluster and multiscale frameworks. We present the modifications to the program since its first major release, eT 1.0, highlighting some notable new features and demonstrating the performance of the new version relative to the first release and to other established electronic structure programs.

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Publication Details

Journal
The Journal of Chemical Physics
Published
2026-04-06
DOI
https://doi.org/10.1063/5.0309334
Primary Topic
Advanced Chemical Physics Studies
Type
article
Field-Weighted Citation Impact
0.00

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article

e T 2.0: An efficient open-source molecular electronic structure program

Torsha Moitra, Matteo Castagnola, Ida‐Marie Høyvik, Linda Goletto et al.
The Journal of Chemical Physics
Advanced Chemical Physics Studies
article

e T 2.0: An efficient open-source molecular electronic structure program

Torsha Moitra, Matteo Castagnola, Ida‐Marie Høyvik, Linda Goletto, Alice Balbi, Eirik F. Kjønstad, Rolf H. Myhre, Tor S. Haugland, Sander Roet, Anna Kristina Schnack‐Petersen, Gioia Marrazzini, Sara Angelico, Rosario R. Riso, Tommaso Giovannini, Bendik Støa Sannes, Alexander C. Paul, Henrik Koch, Andreas S. Skeidsvoll, Sonia Coriani, Guillaume Thiam, Jacob Pedersen, Enrico Ronca, Sarai Dery Folkestad, Alberto Barlini, Daniel Hollas, Marcus T. Lexander, Yassir El Moutaoukal, Riccardo Alessandro, Andrea Bianchi, Jan Haakon M. Trabski, Leo Stoll, Doroteja Lipovec, Ylva Os, Federico Rossi, Chiara Cappelli, Regina Paul
article en

Abstract

The eT program is an open-source electronic structure program with an emphasis on performance and modularity. As its name suggests, the program features extensive coupled cluster capabilities, performing well compared to other electronic structure programs and, in some cases, outperforming commercial alternatives. However, eT is more than a coupled cluster program; other models based on wave function theory (such as full and reduced-space configuration interaction and a variety of self-consistent field models) and density functional theory are supported. The second major release of the program, eT 2.0, has specialized functionality for strong light–matter coupling conditions. In addition, it includes a wide range of optimizations and algorithmic improvements, as well as new capabilities for exploring potential energy surfaces and for modeling experiments in the ultraviolet and X-ray regimes. Molecular gradients are now available at the coupled cluster level, and high-accuracy spectroscopic simulations are available at reduced computational cost within the multilevel coupled cluster and multiscale frameworks. We present the modifications to the program since its first major release, eT 1.0, highlighting some notable new features and demonstrating the performance of the new version relative to the first release and to other established electronic structure programs.

The Journal of Chemical PhysicsVol. 164(13)
University of Rome Tor Vergata (IT), Norwegian Meteorological Institute (NO), Scuola Normale Superiore (IT), University of Applied Sciences Utrecht (NL), Utrecht University (NL), Norwegian University of Science and Technology (NO), University of Perugia (IT), University of Bristol (GB), University of Bergen (NO), Comenius University Bratislava (SK), UiT The Arctic University of Norway (NO), Technical University of Denmark (DK)
European Commission, Novo Nordisk, Danmarks Frie Forskningsfond, Danmarks Tekniske Universitet, Norges Forskningsråd, H2020 European Research Council, HORIZON EUROPE Marie Sklodowska-Curie Actions, HORIZON EUROPE European Research Council
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