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

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• The eT program is an open-source electronic structure computational tool.
• It emphasizes performance and modularity, featuring extensive coupled cluster capabilities.
• It supports various wave function theory and density functional theory models.

Purpose of the Study:

• To present modifications and new features in the eT program's second major release (eT 2.0).
• To highlight performance improvements and new functionalities compared to eT 1.0 and other electronic structure programs.
• To showcase specialized capabilities for strong light-matter coupling and advanced spectroscopic simulations.

Main Methods:

• Development and implementation of new algorithms and optimizations within the eT program.
• Inclusion of specialized functionality for strong light-matter coupling.
• Addition of capabilities for exploring potential energy surfaces and modeling UV/X-ray experiments.

Main Results:

• eT 2.0 demonstrates competitive and, in some cases, superior performance compared to commercial alternatives.
• Molecular gradients are now available at the coupled cluster level.
• High-accuracy spectroscopic simulations are achievable at reduced computational cost using multilevel and multiscale frameworks.

Conclusions:

• eT 2.0 represents a significant advancement in open-source electronic structure software.
• The program offers enhanced capabilities for theoretical chemistry research, particularly in spectroscopy and light-matter interactions.
• Continued development provides a powerful and accessible tool for computational chemistry applications.