Jacek Rychlewski was born September 26, 1947, in Poznan, Poland. He received his Master's Degrees in Mathematics in 1969 and in Chemistry in 1970 from Adam Mickiewicz University in Poznan.

In 1970 he became a research assistant at the Department of Chemistry of A. Mickiewicz University. In 1971 he moved to the University of Warsaw and joined the Wodzimierz Kołos' group in the Department of Chemistry. In 1975 he received his PhD in chemistry for a thesis entitled: Interaction between the B1 and C1u states of the Hydrogen Molecule. In 1974 he returned to A. Mickiewicz University, where he was appointed associate professor in 1986, and full professor in 1992. From 1995 onward, he served as a professor of computational chemistry at the Institute for Bioorganic Chemistry of the Polish Academy of Sciences in Poznan.

As early as 1974, Jacek Rychlewski was working at various foreign scientific institutions such as the University of Florida, Gainesville, Florida (US), the University of Sheffield (UK), the University of North Carolina at Chapel Hill, North Carolina (US), or the University of Wyoming at Laramie, WY (US). Rychlewski's list of scientific publications contains more than 100 original articles devoted to a broad range of problems in theoretical and computational chemistry and molecular physics. He made important contributions to such diverse fields as the theory of molecular structure, especially excited states, the spectroscopy of the hydrogen molecule, interactions between molecules and electric and magnetic fields, the adiabatic approximation, applications of explicitly correlated wavefunctions in chemistry and physics, the theory of the hydrogen bond, molecular effects in -decay, and high-performance computing and parallelization for various systems.

His most outstanding achievements were high-accuracy quantum mechanical treatments of 2-, 3-, and 4-electron molecular systems. By developing novel approximate schemes at Born-Oppenheimer, adiabatic, nonadiabatic, and relativistic levels, he achieved an accuracy matching the best contemporary experiments. Together with coworkers, he developed original methods based on explicitly correlated wavefunctions and, using these methods, he obtained the most accurate theoretical results for such systems as H2 in its ground and excited states, H, HeH+, H3, He, He2, and LiH. These results still serve as benchmarks for both theory and experiment.

Another area in which Rychlewski worked was the study of the interactions of molecules with external fields. He made important contributions by performing very accurate calculations of molecular parameters such as polarizability, magnetizability, rotational g-factor and nuclear shielding for the hydrogen molecule in its ground and excited states. The most spectacular finding was the temperature-independent paramagnetism of this molecule in its B and B 1 states. Besides the ground state of the hypothetical BH molecule, the above states are the only well-documented states for this property. It was suggested that this type of paramagnetism might be common among excited states of diatomic molecules. Rychlewski was also engaged in the study of the adiabatic approximation and, in a series of papers, he showed that double-minimum potential-energy curves can appear as an exclusive result of adiabatic effects. This was found on two pairs of states of H2, h and g and 4s and 4d 3. The same effect was found recently on the r and w 3g states.

Rychlewski served as an advisory editor of Progress in Theoretical Chemistry and Physics and as the executive editor of Computational Methods in Science and Technology. He was a member of the Management Committee of the European Union COST-D9 and COST-D26 actions and was the coordinator of the COST-D9/013 working group, which was devoted to the theory of explicitly correlated wave functions and their applications in theoretical chemistry and physics.

Rychlewski devoted much of his energy and talent to his educational and administrative duties. In 1992 he engaged in creating supercomputing and networking centers for computational chemistry and physics in Poland. From 1998 to 2001, he served as Chairman of the State Committee for Scientific Research, as an advisor for scientific and innovative policy to the Minister of Science, and as a member of the Polish Prime Minister's Advisory Council for Informatics. As a member of the National Council for Science of Solidarnosc, he made significant contributions to the reform of the academic education and to scientific codification.

For outstanding contributions, Rychlewski was awarded the Scientific Prize of the City of Poznan and the Prize of the Polish Chemical Society. Rychlewski's wife, Urszula, to whom he was married for 33 years, is a professor of chemistry and crystallography at A. Mickiewicz University. Rychlewski was fond of history and had a deep knowledge of this field, ranging from ancient civilizations to modern times.

On May 27, 2003, at the age of 55, Jacek Rychlewski passed away suddenly, while working late in his office on a book presenting the theory and applications of explicitly correlated wavefunctions. This book was completed by his collaborators and appeared in the PTCP bookseries.

His death was a great loss to the whole scientific community.