Assessing the accuracy of new geminal-based approaches

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Accurate description of bond dissociation is crucial in chemistry.
• Standard quantum chemistry methods can be computationally expensive for studying bond-breaking.
• Geminal-based wave function ansätze offer a potential alternative.

Purpose of the Study:

• To systematically investigate the performance of novel geminal-based wave function ansätze.
• To assess the accuracy of these methods for diatomic molecule dissociation and spectroscopic constants.
• To compare their efficiency against standard quantum chemistry techniques.

Main Methods:

• Application of antisymmetric product of rank two geminals (APr2G).
• Utilization of antisymmetric product of 1-reference-orbital geminals (AP1roG) and its orbital-optimized variant (OO-AP1roG).
• Comparison with established quantum chemistry methods.

Main Results:

• Geminal-based approaches (APr2G, AP1roG, OO-AP1roG) show robust performance in describing bond dissociation.
• These methods provide accurate spectroscopic constants for diatomic molecules.
• The orbital-optimized variant (OO-AP1roG) demonstrates excellent agreement with reference data.
• The new methods require only mean-field computational cost.

Conclusions:

• Geminal-based wave function ansätze are a cheap, robust, and accurate alternative for studying bond-breaking in closed-shell systems.
• OO-AP1roG is particularly promising for precise calculation of spectroscopic constants.
• These methods offer a computationally efficient route to high-accuracy results in quantum chemistry.