OpenMolcas: From Source Code to Insight.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• The transition from commercial MOLCAS to the open-source OpenMolcas platform.
• Incorporation of numerous new developments and features.

Purpose of the Study:

• Introduce the OpenMolcas environment and its capabilities.
• Invite collaboration from the computational chemistry community.
• Detail recent advancements in theoretical chemistry methods and software.

Main Methods:

• Stochastic complete active space self-consistent field (CASSCF) methods.
• Density Matrix Renormalization Group (DMRG) algorithms.
• Hybrid multiconfigurational wave function and density functional theory (DFT) models.
• Methods for conical intersection optimization and molecular dynamics simulations.
• Interfaces for semiclassical and quantum mechanical nuclear dynamics.
• Advanced simulation features for spectroscopic and magnetic phenomena.
• Post-calculation analysis and visualization tools.
• Frozen-density embedding theory for multiscale simulations.
• New electronic and muonic basis sets.

Main Results:

• Presentation of novel wave function methods and hybrid models.
• Description of enhanced potential energy surface exploration techniques.
• Details on unique simulation features for spectroscopy and magnetic properties.
• Introduction of comprehensive support features for analysis and multiscale simulations.

Conclusions:

• OpenMolcas provides a robust and extensible platform for computational chemistry research.
• The open-source nature fosters community engagement and further development.
• The suite offers state-of-the-art capabilities across various domains of theoretical chemistry.