The variational method complemented with the use of explicitly correlated Gaussian basis
functions is one of the most powerful approaches currently used for calculating the …

Since the early work of Hylleraas on the helium atom, 1 it has been common knowledge that,
to accurately account for the interaction between the electrons in an atom or a molecule …

The dissociation energies from all rovibrational levels of H2 and D2 in the ground electronic
state are calculated with high accuracy by including relativistic and quantum …

The dissociation energy of molecular hydrogen is determined theoretically with a careful
estimation of error bars by including nonadiabatic, relativistic, and quantum electrodynamics …

We have derived the complete formula for the α 7 m contribution to energy levels of an
arbitrary triplet state of the helium atom, performed numerical calculations for the 2 3 S and 2 …

Recent advances regarding the interplay between ab initio calculations and metrology are
reviewed, with particular emphasis on gas-based techniques used for temperature and …

Precision physics aims to use atoms and molecules to test and develop the fundamental
theory of matter, possibly beyond the Standard Model. Most of the atomic and molecular …

We critically examine the current status of theoretical calculations of the energies, the fine
structure, and the isotope shift of the lowest-lying states of helium, searching for unresolved …

In a recent breakthrough in first-principles calculations of two-electron systems, Patkóś,
Yerokhin, and Pachucki [Phys. Rev. A 103, 042809 (2021) PLRAAN 2469-9926 …

A rigorous quantum electrodynamical calculation is presented for energy levels of the 1 1 S,
2 1 S, 2 3 S, 2 1 P 1, and 2 3 P 0, 1, 2 states of helium-like ions with the nuclear charge Z …