Dionys Baeriswyl

Dionys Baeriswyl
Dionys Baeriswyl (1944-2023)
Born	(1944-06-23)23 June 1944
Died	9 August 2023(2023-08-09) (aged 79)
Known for	the Baeriswyl wave function

Dionys Baeriswyl (23 June 1944 – 9 August 2023), son of Alois (1899–1985) and Maria Elisabeth Baeriswyl-Notter (1908-1964), was a Swiss theoretical physicist and Emeritus Full Professor from the University of Fribourg, Switzerland, who worked on Condensed matter physics. Baeriswyl was known primarily for his contributions to the theory of strongly correlated electron systems. In particular, he had conducted fundamental work on conjugated polymer and other quasi-one-dimensional electronic systems, emphasizing early on the importance of electronic correlations in these systems. In addition, Baeriswyl was known for his work on variational wave function approaches to one- and two-dimensional correlated electron systems, applying them to the Peierls transition and the Mott transitions as well as to superconductivity in high-Tc cuprate. In the course of this work, he introduced the variational wave function known as the Baeriswyl wave function, which can be viewed as the strong-coupling complement to the Gutzwiller wave function. While the Gutzwiller wave function incorporates correlation effects into the free electron state, the Baeriswyl wave function incorporates itinerant electron movement into a localized, strongly correlated insulating state.

Education

Dionys Baeriswyl attended gymnasium at the benedictine college in Sarnenwhere he discovered his passions for natural science, foreign languages and music, especially the piano and organ. He concluded his studies in physics in 1969 at the University of Basel with a diploma in theoretical nuclear physics. In 1973 he earned his Ph D at the University of Geneva with a thesis on the theory of elementary excitations in superfluid helium. In 1979 he obtained the teaching diploma of higher education of the Canton of Zurich. In 1985 he was given his Venia Legendi at the ETH Zurich with a habilitation thesis on theoretical aspects of conducting polymers.

Free-lance physicist

In 1982, Baeriswyl resigned a permanent postion as a staff member in the RCA Laboratories in 1982 to allow a colleague with a young family to assume that position. As a consequence, Baerisyl became a “free-lance physicist” between the years of 1982 and 1989. During this period he visited many institutions in Switzerland (ETH Zurich, École polytechnique fédérale de Lausanne, University of Geneva, University of Neuchâtel, IBM Rüschlikon, Brown, Boveri & Cie), Germany (University of Stuttgart, Max Planck Society), Austria (University of Vienna , University of Graz), France (Paris-Saclay University, CEA-Grenoble), Denmark (Technical University of Denmark), United States (Los Alamos National Laboratory, University of Southern California), Russia (Ioffe Institute, Chemico-Technical Institute and Lebedev Physical Institute in Moscow), Ukraine (Taras Shevchenko National University of Kyiv), Italy (University of Trieste, University of Pavia, International Centre for Theoretical Physics, Institute for Scientific Interchange), and Brazil (State University of Campinas).

Academic career

Baeriswyl led the Institute of Theoretical Physics at the University of Fribourg from 1989 until 2000, served as the Dean (education) of the Faculty of Science between 2002 and 2004, and became the President of the Department of Physics from 2007-2009. In 2003, he successfully opposed to severe budget cuts by publicly defending the faculty: La faculté des sciences est une entreprise saine

Fribourg Center for Nanomaterials (FriMat)

During his tenure as Dean of the Faculty of Science at the University of Fribourg, Dionys Baeriswyl encountered Swiss Entrepreneur Adolphe Merkle to discuss the granting of the honorary doctorate at the Dies Academicus on 15 November 2003. Merkle donated in 2006, among other through Baeriswyl’s facilitation, 100 million Swiss Franc to the University of Fribourg for the foundation of a new scientific institute for nanomaterials (FriMat), later called Adolphe Merkle Institute.

Organisor of conferences

Baeriswyl organized numerous conferences and actively participated in establishing new series of events and meetings, e.g. the series of meetings at Gwatt (at the Lake Thun, from 1977-1993), at the Institute for Scientific Interchange (Turin, Italy) and at Évora, Portugal. Together with Mario Rasetti, David Kelly Campbell, and other colleagues, he helped create the extended workshops at the ISI in Turin, established just after the discovery of high-Tc superconductivity. Beginning in 1987 with a group of seven scientists from six countries, these workshops expanded to involve large groups of scientists in a “moveable feast” of brainstorming on that challenging topic for several months a year during the period from 1987-1991. Between 1989 and 2019, Baeriswyl collaborated closely with José Manuel Pereira Carmelo and other physicists as an organizer of many international workshops held in Évora, Portugal. These events brought speakers from around the world and contributed significantly to the scientific education of young researchers, mainly from Portugal and Spain. In 1993, Baeriswyl and Campbell organized a NATO Advanced Research Workshop on “The Hubbard model: Its Physics and Mathematical Physics” in San Sebastián, Spain, and produced a published proceedings with Plenum Press with the same title that has served as a contribution to the archival literature.

Advisor of the International Institute of Physics (IIP) in Natal, Brazil

Dionys Baeriswyl served on the International Advisory Council (IAC) of the International Institute of Physics (IIP) in Natal, Rio Grande do Norte, Brazil, for six years beginning with its creation in 2009.

Dionys Baeriswyl (1944-2023) in the auditorium of the International Institute of Physics in Natal, Brazil

The IAC provided the academic leadership of the IIP, guiding the academic programs, new hirings of research leaders, and the development of new research areas. At the IIP, Baeriswyl was also directly involved in the organization of several scientific meetings in condensed matter physics and related topics. After leaving the board, he became an IIP Distinguished Professor

Trivia

Dionys Baeriswyl on a mountain tour near Zermatt, Switzerland

• Dionys Baeriswyl was a passionate alpinist and conquered many summits in the Swiss Alps and abroad.
• Since his youth he was a passionate Piano and organ player who gave concerts in private and public places.
• His father Alois served in the Swiss Guard under Pope Pius XI from 1922-1938.

Publications

A list of his references includes

- on polymers:

• D.B. and K. Maki, Electron Correlations in Polyacetylene, Physical Review B 31, 6633 (1985)
• D.B., D.K. Campbell, and S. Mazumdar, An Overview of the Theory of pi-Conjugated Polymers, in H.G. Kiess (Ed.), Conjugated Conducting Polymers, Springer Series in Solid-State Sciences 102 (Springer, Berlin, 1992), p. 21

- on the Baeriswyl variational wave function:

• D.B., Variational schemes for Many-Electron Systems, in A.R. Bishop et al. (Ed.), Nonlinearity in Condensed Matter, Springer Series in Solid State Sciences 69 (Springer, Berlin, 1987), p. 183
• M. Dzierzawa, D.B., and M. Di Stasio, Variational wave functions for the Mott transition: The 1/r Hubbard chain, Physical Review B 51, 1993(R) (1995)

Other publications available through Research Gate

Co-authors

Among his co-authors on work on conjugated polymers, other one-dimensional systems, and the Hubbard model are Alan R. Bishop, David Kelly Campbell, Kazumi Maki, Sumit Mazumdar, José Manuel Pereira Carmelo, Cristiane de Morais Smith, and others.