# Ruiz Group

## PD Dr. María Belén Ruiz Ruiz

- Organization: Department of Chemistry and Pharmacy
- Working group: Theoretical Chemistry
- Phone number: +49 9131 85-27772
- Fax number: +49 9131 85-27736
- Email: maria.belen.ruiz@fau.de
- Website: https://chemistry.nat.fau.eu/ruiz-group/
- Address:

Egerlandstr. 3

91058 ErlangenRoom TH 1.474

#### Research

My research lies on the one hand in Quantum Chemistry / Atomic Physics and the development of highly accurate quantum mechanical methods, and on the other hand in their applications to problems in Chemistry, Physics, Medicine and Technology. The Hylleraas-Configuration Interaction (Hy-CI) method is a powerful predictive tool to explain experiments with the help of quantum mechanics and stimulate new experiments. This method allows the calculation of the ground, low-lying excited states and Rydberg states ‘exact’ for physical purposes. Also, using the Hy-CI wave functions we can construct and draw the spectral diagrams of light atoms, as so as to calculate various properties like excitation energies, ionization potentials, absorption probabilities, transition probabilities and probabilities of ionization, among others. A further topic of my research is the mathematical evaluation of integrals over Slater orbitals. We are currently investigating the two- and three-center integrals over Slater-type orbitals. Slater orbitals are the natural basis of orbitals in quantum mechanical calculations, but their use is limited due to the difficulty to solve efficiently all the integrals which appear in a molecular calculation. Therefore in the practice, Gaussian orbitals are used in quantum mechanical calculations of molecules. Nevertheless, the research on integrals over Slater orbitals has never stopped over the years, because Slater orbitals are appropriate for the physical description of the electronic interactions among atoms.