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Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes Using Ion Mobility-Mass Spectrometry
Published on: June 8, 2022
Interactions in diatomic dimers involving closed-shell metals
Konrad Patkowski1, Rafał Podeszwa, Krzysztof Szalewicz
1Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA.
The Journal of Physical Chemistry. A
|November 21, 2007
Summary
Investigating metallic dimers reveals that standard electronic-structure methods struggle with accuracy due to atomic quasidegeneracy. Advanced extrapolated coupled-cluster and full configuration interaction calculations are needed for reliable interaction energies.
Area of Science:
- Computational chemistry
- Quantum chemistry
- Atomic and molecular physics
Background:
- Metallic dimers, including alkaline earth metals (Be, Mg, Ca), Zn, and He-Mg, present computational challenges.
- Quasidegeneracy between ground and excited states of these atoms complicates single-determinant reference state theories.
Purpose of the Study:
- To assess the accuracy of various electronic-structure methods for calculating interaction energies of metallic dimers.
- To understand how computational method performance varies across different metallic elements.
Main Methods:
- Symmetry-Adapted Perturbation Theory (SAPT)
- Supermolecular (SM) methods
- Coupled-cluster method with single, double, and noniterative triple excitations [CCSD(T)]
- Extrapolation to the complete basis set limit
- Full Configuration Interaction (FCI) calculations with a frozen-core (FC) approximation
Main Results:
- Single-determinant-based methods, including CCSD(T), yield unreliable interaction energies for these metallic dimers.
- Accurate interaction energies (within a few percent) are achievable via CCSD(T) extrapolated to the complete basis set limit, followed by FCI/FC calculations.
- Symmetry-Adapted Perturbation Theory (SAPT) errors were traced to approximations in exchange components, which, when corrected, yielded results comparable to CCSD(T).
Conclusions:
- Reliable interaction energy calculations for metallic dimers require advanced methods beyond standard single-determinant approaches.
- Full Configuration Interaction (FCI) calculations, where feasible, provide benchmark estimates for binding energies.
- Correcting approximations in SAPT significantly improves its accuracy and enables physical interpretation of interactions in metallic dimers.
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