International Conference on Precision Physics of Simple Atomic Systems

Spin-dependent terms of the Breit-Pauli Hamiltonian evaluated with an explicitly correlated Gaussian basis set for molecular computations

19 May 2026, 17:56

1m

Aula (ÖAW)

Poster Poster Session 2

Speakers

Peter Hollosy (MTA–ELTE Lendület ‘Momentum’ Molecular Quantum electro-Dynamics Research Group, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, Budapest, H-1117, Hungary) Péter Jeszenszki (MTA–ELTE Lendület ‘Momentum’ Molecular Quantum electro-Dynamics Research Group, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, Budapest, H-1117, Hungary)

Description

This work collects the spin-dependent leading-order relativistic and quantum-electrodynamical corrections for the electronic structure of atoms and molecules within the non-relativistic quantum electrodynamics.$^1$ We report the computation of perturbative corrections using an explicitly correlated Gaussian basis set, which allows high-precision computations for few-electron systems. In addition to numerical tests for triplet $\mathrm{Be}$, triplet $\mathrm{H}_2$, and triplet $\mathrm{H}_3^+$ states and comparison with no-pair Dirac-Coulomb-Breit Hamiltonian energies,$^{2}$ numerical results are reported for electronically excited states of the triplet helium dimer, $\mathrm{He}_2$, for which the present implementation delivers high-precision magnetic coupling curves necessary for a quantitative understanding of the fine structure of its high-resolution rovibronic spectrum.$^{3-4}$

References

$[$1$]$ Jeszenszki, Hollósy, Margócsy, Mátyus, ACS Phys. Chem. Au 5, 618 (2025)
$[$2$]$ D. Ferenc, P. Jeszenszki, and E. Mátyus J. Chem. Phys 157, 094113 (2022).
$[$3$]$ Á. Margócsy, B. Rácsai, P. Jeszenszki, and E. Mátyus, J. Chem. Theory Comput. 22, 2405 (2026)
$[$4$]$ B. Rácsai, P. Jeszenszki, Á. Margócsy, and E. Mátyus, J. Chem. Phys. 163, 081102 (2025)