# Quantum-chemical calculations for ultracold molecular physics experiments

Michal Tomza Faculty of Physics, University of Warsaw, Poland

I will present how molecular electronic structure and quantum scattering calculations can support and explain ultracold quantum physics experiments. Quantum-chemical calculations of potential energy curves [1], permanent and transition electric dipole moments [2], fine and hyperfine coupling constants [3] provide parameters for effective Hamiltonians describing nuclear dynamics. Multichannel quantum scattering calculations give scattering lengths, elastic, inelastic, and reactive rate constants [4,5,6]. I will discuss the capabilities and limits of state-of-the-art methods applied to neutral and ionic systems based on alkali-metal and alkaline-earth-metal atoms, and present our recent results for ongoing experimental effors.

**Figure 1.** Interaction energy as a function of the internuclear distance for the a3Σ+ electronic state of the NaLi molecule from calculations at different levels of theory

[1] M. Gronowski, A. M. Koza, M. Tomza, Phys. Rev. A 102, 020801(R) (2020)

[2] M. Śmiałkowski, M. Tomza, Phys. Rev. A 103, 022802 (2021)

[3] K. Jachymski, M. Gronowski, M. Tomza, Phys. Rev. A 106, L041301 (2022)

[4] P. Weckesser, F. Thielemann, D. Wiater, A. Wojciechowska, L. Karpa, K. Jachymski, M. Tomza, T. Walker, T. Schaetz,Nature 600, 429 (2021)

[5] T. Feldker, H. Fürst, H. Hirzler, N. V. Ewald, M. Mazzanti, D. Wiater, M. Tomza, R. Gerritsma, Nature Phys. 16, 413 (2020)

[6] A. D. Dörfler, P. Eberle, D. Koner, M. Tomza, M. Meuwly, S. Willitsch, Nature Commun. 10, 5429 (2019)