Advanced concepts in theoretical high-resolution rovibrational spectroscopy

• Applicant: Professor Dr. Guntram Rauhut
• Subject Area: Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548811419

The quantum chemical calculation of accurate rotational and rovibrational spectra without relying on model Hamiltonians is a demanding task and is currently limited to systems with about 6 or 7 atoms. The limitations arise from an extreme rovibrational state density, the increase of the required rotational quantum number for larger systems, the importance of hot bands and so on. However, many molecular systems beyond that size have been observed in the interstellar medium or circumstellar shells, whose investigation would significantly profit from such methods. Consequently, there is a high need to extend the capabilities of current approaches to molecules with up to 10 or 12 atoms. Within this proposal, refinements to rovibrational configuration interaction theory (RVCI) are suggested, which aim at an acceleration and automatization of such calculations and studies. These range from prescreening techniques and sparsity concepts to state-selection and minimization concepts. The improved code shall be applied to the investigation of astrophysically relevant molecules with an emphasize on chiral systems.

• DFG Programme: Research Grants