Alkali - Earth Diatomics: Molecules for Ultracold Physics

Ultracold diatomic molecules find application in quantum studies ranging from controlled chemistry and precision measurement physics to quantum many-body simulation and potentially quantum computing. Accurate knowledge of molecular properties is required to guide and explain ongoing experiments. Here, in an extensive and comparative study, we theoretically investigate the electronic properties of the ground-state diatomic molecules composed of alkali-metal (Li, Na, K, Rb, Cs, Fr) and alkaline-earth-metal (Be, Mg, Ca, Sr, Ba, Ra) atoms. We study 78 heteronuclear and homonuclear diatomic combinations, including 21 alkali-metal molecules in the ${X}^{1}{\mathrm{\ensuremath{\Sigma}}}^{+}$ and ${a}^{3}{\mathrm{\ensuremath{\Sigma}}}^{+}$ electronic states, 36 alkali-metal--alkaline-earth-metal molecules in the ${X}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}$ electronic state, and 21 alkaline-earth-metal molecules in the ${X}^{1}{\mathrm{\ensuremath{\Sigma}}}^{+}$ electronic state. We calculate potential energy curves, permanent electric dipole moments, and polarizabilities using the hierarchy of coupled-cluster methods up to CCSDTQ with large Gaussian basis sets and small-core relativistic energy-consistent pseudopotentials. We collect and analyze corresponding spectroscopic constants. We estimate computational uncertainties and compare the present values with previous experimental and theoretical data to establish a different theoretical benchmark. The presented results should be useful for further application of the studied molecules in modern ultracold physics and chemistry experiments.Ultracold diatomic molecules find application in quantum studies ranging from controlled chemistry and precision measurement physics to quantum many-body simulation and potentially quantum computing. Accurate knowledge of molecular properties is required to guide and explain ongoing experiments. Here, in an extensive and comparative study, we theoretically investigate the electronic properties of the ground-state diatomic molecules composed of alkali-metal (Li, Na, K, Rb, Cs, Fr) and alkaline-earth-metal (Be, Mg, Ca, Sr, Ba, Ra) atoms. We study 78 heteronuclear and homonuclear diatomic combinations, including 21 alkali-metal molecules in the ${X}^{1}{\mathrm{\ensuremath{\Sigma}}}^{+}$ and ${a}^{3}{\mathrm{\ensuremath{\Sigma}}}^{+}$ electronic states, 36 alkali-metal--alkaline-earth-metal molecules in the ${X}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}$ electronic state, and 21 alkaline-earth-metal molecules in the ${X}^{1}{\mathrm{\ensuremath{\Sigma}}}^{+}$ electronic state. We calculate potential energy curves, permanent electric dipole moments, and polarizabilities using the hierarchy of coupled-cluster methods up to CCSDTQ with large Gaussian basis sets and small-core relativistic energy-consistent pseudopotentials. We collect and analyze corresponding spectroscopic constants. We estimate computational uncertainties and compare the present values with previous experimental and theoretical data to establish a different theoretical benchmark. The presented results should be useful for further application of the studied molecules in modern ultracold physics and chemistry experiments.

arXiv:2303.17527Physical Review AMay 13, 202435 citations

Controlling the interaction of ultracold alkaline-earth atoms

Ren Zhang, Yanting Cheng, Peng Zhang +1 more

arXiv:1908.04973Nature Reviews PhysicsMar 23, 202036 citations

BONDING OF ALKALI-ALKALINE EARTH MOLECULES IN THE LOWEST Σ+ STATES OF DOUBLET AND QUARTET MULTIPLICITY

Johann Valentin Pototschnig, Wolfgang Ernst, Andreas Hauser

\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.6]{ak_ake.eps} \end{wrapfigure} In the present study the ground state as well as the lowest $^4\Sigma^+$ state were determined for 16 AK-AKE molecules.\footnote{ J. V. Pototschnig, A. W. Hauser and W. E. Ernst, Phys. Chem. Chem. Phys., 2016,18, 5964-5973} Multireference configuration interaction calculations were carried out in order to understand the bonding of diatomic alkali-alkaline earth (AK-AKE) molecules. The correlations between molecular properties (disociation energy, bond distances, electric dipole moment) and atomic properties (electronegativity, polarizability) will be discussed. A correlation between the dissociation energy and the dipole moment of the lowest $^4\Sigma^+$ state was observed, while the dipole moment of the lowest $^2\Sigma^+$ state does not show such a simple dependency. In this case an empirical relation could be established. The class of AK-AKE molecules was selected for this investigation due to their possible applications in ultracold molecular physics.\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.6]{ak_ake.eps} \end{wrapfigure} In the present study the ground state as well as the lowest $^4\Sigma^+$ state were determined for 16 AK-AKE molecules.\footnote{ J. V. Pototschnig, A. W. Hauser and W. E. Ernst, Phys. Chem. Chem. Phys., 2016,18, 5964-5973} Multireference configuration interaction calculations were carried out in order to understand the bonding of diatomic alkali-alkaline earth (AK-AKE) molecules. The correlations between molecular properties (disociation energy, bond distances, electric dipole moment) and atomic properties (electronegativity, polarizability) will be discussed. A correlation between the dissociation energy and the dipole moment of the lowest $^4\Sigma^+$ state was observed, while the dipole moment of the lowest $^2\Sigma^+$ state does not show such a simple dependency. In this case an empirical relation could be established. The class of AK-AKE molecules was selected for this investigation due to their possible applications in ultracold molecular physics.

International Symposium on Molecular Spectroscopy (ISMS)Jun 21, 20160 citations

Structure and interactions of atoms and diatomic molecules: from ultracold gases to doped solids

Maxence Lepers

This is the manuscript of my "Habilitation à diriger des recherches", where I present the research work that I have done after my PhD, defended in 2009. The manuscript is divided in two parts. The first one is dedicated to atomic-structure calculations with neutral and trivalent lanthanides, in the contexts of ultracold gases and rare-earth doped solids. The second part deals with long-range interactions in ultracold gases of alkali-metal atoms and diatomic molecules, as well as lanthanide atoms. The detailed description of long-range interactions serves to characterize ultralow-temperature phenomena, like photoassociation and collisional shielding.This is the manuscript of my "Habilitation à diriger des recherches", where I present the research work that I have done after my PhD, defended in 2009. The manuscript is divided in two parts. The first one is dedicated to atomic-structure calculations with neutral and trivalent lanthanides, in the contexts of ultracold gases and rare-earth doped solids. The second part deals with long-range interactions in ultracold gases of alkali-metal atoms and diatomic molecules, as well as lanthanide atoms. The detailed description of long-range interactions serves to characterize ultralow-temperature phenomena, like photoassociation and collisional shielding.

cond-mat.quant-gasCross-listedarXiv:2511.02890Nov 5, 20250 citations

\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.6]{ak_ake.eps} \end{wrapfigure} In the present study the ground state as well as the lowest

^4\Sigma^+

state were determined for 16 AK-AKE molecules.\footnote{ J. V. Pototschnig, A. W. Hauser and W. E. Ernst, Phys. Chem. Chem. Phys., 2016,18, 5964-5973} Multireference configuration interaction calculations were carried out in order to understand the bonding of diatomic alkali-alkaline earth (AK-AKE) molecules. The correlations between molecular properties (disociation energy, bond distances, electric dipole moment) and atomic properties (electronegativity, polarizability) will be discussed. A correlation between the dissociation energy and the dipole moment of the lowest

^4\Sigma^+

state was observed, while the dipole moment of the lowest

^2\Sigma^+

state does not show such a simple dependency. In this case an empirical relation could be established. The class of AK-AKE molecules was selected for this investigation due to their possible applications in ultracold molecular physics.