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Analysis and Assessment of Knowles' Partitioning in Many-Body Perturbation Theory
András Gombás1, Péter R Surján1, Ágnes Szabados1
1Laboratory of Theoretical Chemistry, Institute of Chemistry, Faculty of Science, ELTE Eötvös Loránd University, P.O.B. 32, H-1518 Budapest 112, Hungary.
Journal of Chemical Theory and Computation
|June 7, 2024
Summary
Perturbation Adapted Partitioning (PAPT) offers a novel approach in many-body perturbation theory. This method systematically outperforms traditional partitioning by optimizing molecular orbitals and energies.
Area of Science:
- Computational Chemistry
- Quantum Chemistry
- Theoretical Chemistry
Background:
- Many-body perturbation theory (MBPT) is crucial for accurate electronic structure calculations.
- Traditional partitioning methods, like Møller-Plesset perturbation theory, rely on canonical orbitals and Koopmans' theorem, which can limit accuracy.
- Novel partitioning schemes are needed to improve the efficiency and accuracy of MBPT calculations.
Purpose of the Study:
- To provide a detailed analysis of the recently proposed Perturbation Adapted Partitioning (PAPT) method.
- To investigate the roles of level shift and orbital rotation effects within the PAPT framework.
- To assess the performance of PAPT against canonical partitioning and explore its self-consistent variant.
Main Methods:
- Analysis of perturbation adapted partitioning (PAPT) as proposed by Knowles.
- Separate and combined examination of level shift and orbital rotation effects.
- Testing the self-consistent version of PAPT for energy and convergence.
- Application to a multireference system and van der Waals interactions.
- Mathematical analysis of projection function dependence.
Main Results:
- Level shift and orbital rotation are key components of the zero-order Hamiltonian in PAPT.
- The combined effect of level shift and orbital rotation in PAPT significantly outperforms individual components.
- PAPT, using optimized molecular orbitals and energies, systematically surpasses Møller-Plesset partitioning.
- The self-consistent PAPT shows promising energy and convergence characteristics.
- PAPT accurately describes multireference systems and van der Waals interactions.
Conclusions:
- Perturbation Adapted Partitioning (PAPT) represents a significant advancement in many-body perturbation theory.
- The method's success stems from its ability to determine optimal orbitals and energies, enhancing predictive power.
- PAPT provides a robust and versatile framework for accurate electronic structure calculations.
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