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Updated: Sep 10, 2025

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
High-precision quantum dynamics of He2 over the b 3Πg-c 3Σg+ electronic subspace by including non-adiabatic,
Balázs Rácsai1, Péter Jeszenszki1, Ádám Margócsy1
1MTA-ELTE "Momentum" Molecular Quantum electro-Dynamics Research Group, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, Budapest H-1117, Hungary.
Abstract:
Relativistic, quantum electrodynamics, and non-adiabatic corrections and couplings are computed for the b 3Πg and c3Σg+ electronic states of the helium dimer. The underlying Born-Oppenheimer potential energy curves are converged to 1 ppm (1: 106) relative precision using a variational explicitly correlated Gaussian approach. The quantum nuclear motion is computed over the b 3Πg-c3Σg+ (and B 1Πg-C1Σg+) 9-(12-)dimensional electronic-spin subspace coupled by non-adiabatic and relativistic (magnetic) interactions. The electron's anomalous magnetic moment is also included; its effect is expected to be visible in high-resolution experiments. The computed rovibronic energy intervals are in excellent agreement with the available high-resolution spectroscopy data, including the rovibronic b 3Πg-state fine structure. Fine-structure splittings are also predicted for the c3Σg+ levels, which have not been fully resolved experimentally, yet.
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