In the universe, new galaxies are formed in interstellar clouds of molecules and dust particles that condense locally under the influence of gravity to form proto-stars. Once a star has formed, protoplanetary disks emerge which are the nurseries where new planets are born. Information about the molecular composition, density, temperature, etc., of protoplanetary disks can be obtained from molecular spectra measured using space telescopes like the fairly recently launched James Webb Space Telescope (JWST).
Researchers use models to extract the desired information from these spectra. Important parameters required by these models include the rates of transitions between different energy states of molecules such as CO2, H2O, HCN, C2H2, which arise from collisions with the most common atoms and molecules: helium (He) and hydrogen (H2).
This PhD thesis describes the development of new quantum-mechanical computational methods and algorithms that can be used to calculate the required rate constants accurately and efficiently. These methods have been tested and applied to different vibrational-rotational states of CO2, an important molecule in this context, in collisions with He atoms. The results obtained are now available to astrophysicists and astrochemists for use in their models which are important not only to extract the desired information from the measured spectra, but also to understand, using simulations, how protoplanetary disks evolve into planets. Our results can also be used in interpreting spectra of the atmospheres of other planets and exoplanets.
Taha Selim is a PhD candidate in Theoretical and Computational Chemistry at Radboud University Nijmegen, The Netherlands. His research focuses on developing quantum-mechanical computational methods to calculate collision rate coefficients for rovibrational transitions in molecules. He has also contributed to teaching theoretical and computational chemistry, computational physics, and computer science courses.
Currently, he works as a Quantum Education Officer at the Talent and Learning Center at Amsterdam University of Applied Sciences (AUAS) and is a Quantum Computing Instructor at the Quantum Computing Workshops in Amsterdam. He has taught Physics and Mathematics at the German University in Cairo, the American University in Cairo, and other institutions.
Before his PhD, Selim earned a Master of Science in Physics, Lasers, and Materials from Université de Bourgogne in Dijon, France, and completed his Master's thesis at Université Paris-SUD. He holds a Bachelor's degree in Physics and Mathematics from the American University in Cairo, Egypt.