Transcorrelated coupled cluster methods

Area of Science:

• Quantum Chemistry
• Computational Physics

Background:

• Coupled cluster methods are standard for accurate electronic structure calculations.
• Explicitly correlated methods improve basis set convergence but can be computationally expensive.

Purpose of the Study:

• To introduce and implement novel transcorrelated coupled cluster and distinguishable cluster methods.
• To evaluate the performance of these new methods against conventional and explicitly correlated techniques.

Main Methods:

• Similarity transformation of the Hamiltonian using a Jastrow factor in first quantization.
• Formulation and implementation of coupled cluster with singles and doubles (CCSD) equations on the transformed Hamiltonian.
• Development and testing of approximations for three-body integrals.

Main Results:

• The presented transcorrelated methods demonstrate superior basis set convergence.
• The new methods achieve higher accuracy compared to conventional and explicitly correlated coupled cluster approaches.
• Approximations for three-body integrals were successfully tested.

Conclusions:

• Transcorrelated coupled cluster methods offer a significant advancement in electronic structure calculations.
• These methods provide a more accurate and efficient alternative for quantum chemistry problems.
• Further development of approximations for three-body integrals can enhance computational efficiency.