Egil Hylleraas

Egil Hylleraas, in London in 1934

Egil Andersen Hylleraas , actually Andersen, (born May 15, 1898 in Engerdal , Norway , † October 28, 1965 in Oslo ) was a Norwegian theoretical physicist who dealt with atomic physics and is known for the quantum mechanical treatment of two-electron atoms ( helium ).

Life

Hylleraas was the youngest of eleven children of a teacher and farmer in a small mountain village in southern Norway (Engerdal). The name Hylleraas is the name of the farm, the father was called Ole Andersen. From 1918 he studied mathematics and physics at the University of Oslo (then Christiania) to become a teacher and after graduating in 1924 was a high school teacher in Oslo for a few years. He also wrote articles about birefringence in crystals and received a scholarship to study with Max Born at the University of Göttingen from 1926 to 1928 . With this he first continued his work on crystal lattices (for which Born was considered a specialist), but under the influence of Born turned to the emerging quantum mechanics. In 1931 he became a member of the Christian Michelsen Institute in Bergen , received his doctorate in 1933 at the University of Oslo and in 1937 he succeeded Vilhelm Bjerknes as professor of theoretical physics in Oslo, which he remained until his death from a heart attack.

In 1947/48 he was at the Institute for Advanced Study in Princeton and 1962/63 at the University of Wisconsin – Madison . In the 1950s he was one of the representatives of Norway at the newly founded organizations CERN and Nordita .

In 1963 a symposium was held in his honor at the University of Florida.

In 1932 he became a Fellow of the Royal Society .

Personally, he was reserved and humble.

plant

In 1926 in Göttingen, Hylleraas undertook pioneering work on the application of quantum mechanics in multi-electron atoms, beyond the simple case of hydrogen. At Born's suggestion, he investigated the ionization energy in helium. The old Bohr-Sommerfeld theory gave 28 eV for this , Albrecht Unsöld had in the first order perturbation theory in 1927 20.41 eV, but experimentally it was 24.59 eV. In his first work, Hylleraas found 24.35 eV and further improved the value to 24.47 eV by 1929. This was seen as the success of the new quantum mechanics in the form of Schrödinger's wave mechanics. His newly developed variation methods (named after him today, as well as the wave function approaches used) formed one of the foundations for quantum mechanical calculations in atomic physics and the numerical calculations that he used with a desktop calculator (a Mercedes-Euclid) were some of the first important ones Applications of computational physics. This marked the way forward, which was mainly characterized by the availability of faster computers.

In 1930 he and Hans Bethe proved the stability of the negative hydrogen ion (i.e. a hydrogen nucleus with two electrons), which was detected in the solar atmosphere in 1938 (see photosphere ). He also dealt with the quantum mechanics of molecules and lattices, such as lithium hydride in 1930, followed by further work on diatomic molecules in the 1930s. He also treated atoms such as boron, beryllium and carbon in the 1930s, often in collaboration with the Swedish spectroscope Bengt Edlén . He also dealt with nuclear physics, but this remained largely unpublished.

From 1939 to 1943 he dealt with the theory of tides. After the Second World War, he devoted himself mainly to organizational tasks at the University of Oslo and training in theoretical physics in Norway. He continued his occupation with the helium atom and the hydrogen ion with his students and dealt with relativistic electron theory, scattering theory and spinors.

Fonts

Reminiscences from Early Quantum Mechanics of Two-Electron Atoms , Proceedings of the International Symposium on Atomic and Molecular Quantum Mechanics in Honor of Egil A. Hylleraas, Reviews of Modern Physics, Volume 35, 1963, pp. 421-431.
Mathematical and Theoretical Physics, New York 1970 (Norwegian original in 4 volumes, Oslo 1950–1952).
Hylleraas On the basic term of the two-electron problems of H−, He, Li +, Be ++ etc. , Z. f. Physik, Volume 65, 1930, pp. 209-225.
Hylleraas The basics of quantum mechanics with applications to atom-theoretical one- and multi-electron problems , Norsk Vid. Akad. Skrift., Mat.-Naturv. Kl., Oslo, 1932, No. 6.

literature

OK Gjøtterud, obituary with bibliography, Nuclear Physics, Volume 89, 1966, pp. 1-10.
H. Wergeland, obituary in Fra Fysikkens Verden, Volume 28, 1966, pp. 1-10.
Hans Bethe, Edwin Salpeter Quantum mechanics of one and two electron atoms , in Siegfried Flügge (Ed.) Handbuch der Physik / Encyclopedia of Physics , Volume 35, Springer Verlag 1957.

Web links

Commons : Egil Hylleraas - Collection of images, videos and audio files

Per Strømholm, Dictionary of Scientific Biography 2008

Individual evidence

↑ He later described Born's dynamics of crystal lattices and Arnold Sommerfeld's atomic structure and spectral lines as the greatest influences

↑ Membership Book of the IAS, 1980

↑ Unsöld, Annalen der Physik, Volume 82, 1927, p. 355

↑ Hylleraas new calculation of the energy of helium in the basic state, as well as the lowest term of Ortho-Heliium , Zeitschrift für Physik, Volume 54, 1929, pp. 347-366.

↑ GW Kellner also applied the Ritz method to the helium problem in 1927, G. Kellner The ionization voltage of helium according to Schrödinger's theory , Z. f. Phys., Vol. 44, 1927, pp. 91-109.

↑ Hylleraas' first work on helium is On the ground state of the helium atom , Z. f. Physik, Volume 48, 1928, pp. 469-494.

↑ He chose for the electron wave function a power series in the three variables , , (or , , ), the distance between the electron 1 and 2 and the amount of the distance of the electrons with each other, in addition to the prefactor , with shielded nuclear charge . The Rayleigh-Ritz method was then used.

{\ displaystyle r_ {1}}

{\ displaystyle r_ {2}}

{\ displaystyle r_ {12}}

{\ displaystyle s = r_ {1} + r_ {2}}

{\ displaystyle t = r_ {1} -r_ {2}}

{\ displaystyle u = r_ {12}}

{\ displaystyle e ^ {- \ alpha Z \ cdot (r_ {1} + r_ {2})}}

{\ displaystyle \ alpha Z}

↑ Hylleraas The electron affinity of the hydrogen atom according to wave mechanics , Z. f. Physik, Volume 60, 1930, pp. 624-630.

↑ See also Hylleraas The negative hydrogen ion in quantum mechanics and astrophysics , Astrophysica Norvegica, Volume 9, 1964, p. 345 Online

↑ Bethe calculation of the electron affinity of hydrogen , Z. f. Physik, Volume 57, 1929, pp. 815-821. He refers explicitly to Hylleraas (1929) and uses his approach.

↑ Hylleraas wave mechanical calculation of the lattice energy and the lattice constant of lithium hydride , Zeitschrift für Physik, Volume 63, 1930, pp 771–794

personal data
SURNAME	Hylleraas, Egil
ALTERNATIVE NAMES	Andersen, Egil
BRIEF DESCRIPTION	Norwegian physicist
DATE OF BIRTH	May 15, 1898
PLACE OF BIRTH	Engerdal
DATE OF DEATH	October 28, 1965
Place of death	Oslo

[1] He later described Born's dynamics of crystal lattices and Arnold Sommerfeld's atomic structure and spectral lines as the greatest influences

[2] Membership Book of the IAS, 1980

[3] Unsöld, Annalen der Physik, Volume 82, 1927, p. 355

[4] Hylleraas new calculation of the energy of helium in the basic state, as well as the lowest term of Ortho-Heliium , Zeitschrift für Physik, Volume 54, 1929, pp. 347-366.

[5] GW Kellner also applied the Ritz method to the helium problem in 1927, G. Kellner The ionization voltage of helium according to Schrödinger's theory , Z. f. Phys., Vol. 44, 1927, pp. 91-109.

[6] Hylleraas' first work on helium is On the ground state of the helium atom , Z. f. Physik, Volume 48, 1928, pp. 469-494.

[7] He chose for the electron wave function a power series in the three variables , , (or , , ), the distance between the electron 1 and 2 and the amount of the distance of the electrons with each other, in addition to the prefactor , with shielded nuclear charge . The Rayleigh-Ritz method was then used. ${\ displaystyle r_ {1}}$ ${\ displaystyle r_ {2}}$ ${\ displaystyle r_ {12}}$ ${\ displaystyle s = r_ {1} + r_ {2}}$ ${\ displaystyle t = r_ {1} -r_ {2}}$ ${\ displaystyle u = r_ {12}}$ ${\ displaystyle e ^ {- \ alpha Z \ cdot (r_ {1} + r_ {2})}}$ ${\ displaystyle \ alpha Z}$

[8] Hylleraas The electron affinity of the hydrogen atom according to wave mechanics , Z. f. Physik, Volume 60, 1930, pp. 624-630.

[9] See also Hylleraas The negative hydrogen ion in quantum mechanics and astrophysics , Astrophysica Norvegica, Volume 9, 1964, p. 345 Online

[10] Bethe calculation of the electron affinity of hydrogen , Z. f. Physik, Volume 57, 1929, pp. 815-821. He refers explicitly to Hylleraas (1929) and uses his approach.

[11] Hylleraas wave mechanical calculation of the lattice energy and the lattice constant of lithium hydride , Zeitschrift für Physik, Volume 63, 1930, pp 771–794