Egil Andersen Hylleraas

Egil Andersen Hylleraas (May 15, 1898 – October 28, 1965) was a Norwegian theoretical physicist known for creating a method for predicting the ground state energy of two-electron atoms and trial wave functions for many-electron atoms.

Biography Egil Andersen Hylleraas was born in the town of Hylleråsen, Norway in 1898. Hylleraas was the youngest of ten children. which later led to the organization's establishment.

He died in 1965. Hylleraas referred to 1925–1930 as the Golden Age of atomic physics. It was when Bohr's theory of the atom was replaced by the new theory of quantum mechanics. By 1926, the one-electron hydrogen had been solved, and Werner Heisenberg had formulated the two-electron helium problem quantum mechanically. A simple first-order perturbation treatment still yielded considerably increased ionization potential for error with experimental measurement. Max Born considered it crucial for quantum mechanics to provide a result in better agreement with experiments.

When Hylleraas arrived at Göttingen, he learned that Max Born had abandoned crystallography. He continued Max Born's work on crystals independently. Still, he was assigned to work on the helium problem when Bohr's student became ill. Hylleraas modified the first attempt in two ways: he replaced the incomplete bound state hydrogenic functions with the complete Laguerre functions. He reduced the number of coordinates from 6 to 3, namely the distances of the two electrons from the nucleus and the angle between the position vectors of the two electrons. He obtained results in much better agreement with the experiments with a mechanical desk calculator. The result was well received, but the discrepancy of 0.12 eV continued to bother him. A breakthrough was achieved in 1928, when Hylleraas realized the angle coordinate needed to be replaced by the distance between the two electrons. With only three terms in the wave function expansion, the error had been reduced to 0.03 eV, with six terms to 0.01 eV. His work was quickly applied to other two-electron atoms and the hydrogen molecule.

Awards Gunnerus Medal (1960)

Selected publications

(over 1830 citations)