Tensor-structured coupled cluster theory.

Area of Science:

• Quantum Chemistry
• Computational Physics
• Theoretical Chemistry

Background:

• Coupled cluster (CC) methods are highly accurate for electronic structure calculations.
• Traditional CC methods exhibit high computational scaling, limiting their application to larger systems.
• Developing efficient CC solvers is crucial for advancing computational chemistry.

Purpose of the Study:

• To derive and implement a novel computational approach for solving coupled cluster equations.
• To reduce the computational scaling of coupled cluster methods.
• To provide a more accessible and efficient tool for electronic structure calculations.

Main Methods:

• Decomposition of amplitudes and two-electron integrals.
• Application of tensor hypercontraction (THC) and canonical polyadic decomposition (CPD).
• Direct solution for the factors of the cluster operator.

Main Results:

• Achieved a computational scaling of O(N^4) from the original O(N^6).
• Demonstrated numerical accuracy with sub-millihartree difference from the original theory.
• Validated the general applicability of the proposed scheme.

Conclusions:

• The new method significantly lowers the computational cost of coupled cluster calculations.
• This approach enhances the feasibility of accurate electronic structure studies for larger molecular systems.
• The scheme's generality allows for extension to other many-body quantum mechanical methods.