Quasipinning and selection rules for excitations in atoms and molecules

Abstract

Postulated by Pauli to explain the electronic structure of atoms and molecules, the exclusion principle establishes an upper bound of 1 for the fermionic natural occupation numbers $\{n_i\}$. A recent analysis of the pure $N$-representability problem provides a wide set of inequalities for the $\{n_i\}$, leading to constraints on these numbers. This has a strong potential impact on reduced density matrix functional theory as we know it. In this work we continue our study the nature of these inequalities for some atomic and molecular systems. The results indicate that (quasi)saturation of some of them leads to selection rules for the dominant configurations in configuration interaction expansions, in favorable cases providing means for significantly reducing their computational requirements.

12 pages, 15 figures, new references, some typos corrected and a new section added

References in corpus (9)

• The Pauli principle revisited
• Pinning of Fermionic Occupation Numbers
• Generalized Pauli conditions on the spectra of one-electron reduced density matrices of atoms and molecules
• Generalized Pauli constraints in reduced density matrix functional theory
• Quasipinning and its relevance for $N$-Fermion quantum states
• Significant Conditions on the Two-electron Reduced Density Matrix from the Constructive Solution of N-representability
• The Pauli exclusion principle and beyond
• Multipartite Quantum States and their Marginals
• Why doubly excited determinants govern configuration interaction calculations of electron correlations

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• Quantum-classical hybrid algorithm using an error-mitigating $N$-representability condition to compute the Mott metal-insulator transition
• Experimental Data from a Quantum Computer Verifies the Generalized Pauli Exclusion Principle
• Pinning of fermionic occupation numbers: Higher spatial dimensions and spin
• Natural Extension of Hartree-Fock through extremal $1$-fermion information: Overview and application to the lithium atom
• Asymptotic properties of entanglement polytopes for large number of qubits