arXiv subjects

J. J. Lopez-Rodriguez

Publications and source records attributed to J. J. Lopez-Rodriguez.

5 recordsLinked to original sources

arXiv2026

Diagonal Born--Oppenheimer correction in strong magnetic fields: finite-difference approach for light diatomic molecules

The influence of the diagonal Born--Oppenheimer correction (DBOC) on the electronic structure of light diatomic molecules subjected to strong magnetic fields is investigated. H$_2$, HeH$^+$, and LiH are considered, using both the Hartree--Fock (HF) approximation and configuration interaction with single and double excitations (CISD). The analysis covers magnetic field strengths up to $B_\parallel = 0.2$ a.u. ($4.7\times10^{4}$~T), relevant to astrophysical conditions near magnetic white dwarfs. Although the correction noticeably shifts total electronic energies, it varies smoothly with internuclear distance and depends only weakly on the field, so that it enters the vibrational transition frequencies as a nearly field-independent offset, shifting the fundamental interval by about $1$~cm$^{-1}$ and the higher levels by up to $15$ cm$^{-1}$. These shifts exceed the $0.1$--$2.0$ cm$^{-1}$ accuracy currently attainable for molecular lines in the atmospheres of magnetic white dwarfs. Comparison of HF and CISD results shows that electron correlation has a non-negligible effect on the DBOC, most pronounced for the strongly ionic LiH bond.

physics.atom-ph↗

arXiv2026

Long-range magnetic interaction within quantum electrodynamics formalism

Within the framework of quantum electrodynamics, the interaction between two atoms at large distances is analyzed. Using the S-matrix formalism, an expression for the magnetic interaction potential is derived, which agrees with the well-known result of classical electrodynamics. However, quantum electrodynamics goes beyond this conventional result and allows one to treat a wide range of problems related to the structure of atomic energy levels. In particular, it is shown that the asymptotic behavior of the interaction potential can deviate from the classical prediction, depending on the atomic states involved. As an example, dispersion coefficients are calculated for the s-states of hydrogen atoms, where the long-range potential reduces to a spin-spin interaction. The results obtained open up the possibility of a straightforward comparative analysis of long-range interaction potentials between atoms of matter and antimatter. The applicability of this approach is demonstrated for the hydrogen-antihydrogen system.

physics.atom-ph↗

arXiv2026

Non-adiabatic Effects Induced by Strong Light-Matter Coupling in Cavity QED

We present a systematic study of the diagonal Born-Oppenheimer correction (DBOC) for atoms and molecules embedded in optical cavities and interacting with a quantized electromagnetic field. By explicitly evaluating the nuclear kinetic energy operator, we analyze cavity-induced modifications of DBOC within a quantum electrodynamics configuration-interaction (QED-CI) framework built on quantum electrodynamics Hartree-Fock (QED-HF) and strong-coupling quantum electrodynamics Hartree-Fock (SC-QED-HF) reference states. The analysis covers a diverse set of atomic and molecular systems, including He, H-, Be, H2, LiH, HF, ammonia (NH3), and formaldehyde (CH2O). We show that the presence of the cavity leads to shifts in molecular dissociation energies on the order of a few inverse centimeters. For several atomic systems, the inclusion of the DBOC yields a pronounced effect, with the correction magnitude reaching the experimental resolution. These findings reveal finite nuclear mass effects as an essential component of nuclear dynamics in cavity QED and suggest their relevance for precision analysis in strongly coupled light-matter systems.

physics.atom-ph↗

arXiv2026

Applicability of the Dirac-Fock method combined with Core Polarization in calculations of alkali atoms

In this work, we investigate the applicability of the core-polarization-corrected Dirac--Fock method, formulated within the framework of the local Dirac--Hartree--Fock (LDF) potential, for the accurate determination of static scalar and tensor electric dipole polarizabilities. This work presents theoretical values of blackbody-radiation-induced Stark shifts of atomic energy levels. The Dirac--Fock method augmented by core-polarization corrections is employed not only to evaluate these shifts but also to compute the Bethe logarithm for alkali-metal atoms. The results are critically compared with data available in the contemporary literature, and the strengths and limitations of the present approach are discussed.

physics.atom-ph↗

arXiv2025

Multipole decomposition of the thermal one-loop self-energy correction for a bound atomic electron

In this paper, we present a comprehensive analysis of the one-loop self-energy correction at finite temperature for the bound electron. In this approach, we study the influence of thermal radiation on atomic systems. Along the way, we found well-known effects, including thermal Stark and Zeeman shifts, as well as thermal quadrupole interactions and relativistic corrections to the multipole expansion of photon field operators. We show that the corresponding contributions arise from the decomposition of the fully relativistic expression in terms of the $αZ$ parameter. The presented analysis unambiguously determines the consistency of the quantum electrodynamics theory at finite temperature (TQED) with the perturbation theory of quantum mechanics (QM). Although our analysis mainly focuses on the hydrogen atom model, their potential implications for precision spectroscopic experiments are discussed.

physics.atom-ph↗