Maria I. Petrashen
(6.09.1906 - 12.07.1977)
Maria Ivanovna Petrashen was born on September, 6, 1906 in Vologda. Her father was a railway engineer. From him and her English mother, totally devoted to the family, Maria Ivanovna together with her two sisters and three brothers got a good education along with knowledge of three foreign languages. She had also inherited high moral standards prevailing in the family. In 1923 Maria Ivanovna entered the Mathematical Section of the Department of Physics and Mathematics of Leningrad State University and graduated from it in 1929. Her scientific adviser was an outstanding mathematician, afterwards academician Vladimir Ivanovich Smirnov. The professor and the student remained colleagues and friends for life.
After graduation from the University, M.I. Petrashen accepted a position of a mathematician in the State Optical Institute directed at that time by another outstanding personality academician Dmitry Sergeevich Rozhdestvensky. In 1930 he initiated organization of a new research group working in the field of theoretical spectroscopy. This group was headed by still young but already world-famous theoretical physicist Vladimir Alexandrovich Fock. Naturally, members of the group were also young, among them physicists M.G. Veselov, P.P. Pavinsky, A.G. Vlasov and mathematician M.I. Petrashen. Under direction of V.A. Fock, Maria Ivanovna accomplished pioneer calculations on electronic structure of Li and Be atoms using the self-consistent field method with exchange (the famous Hartree-Fock method). Since then this method became one of the most popular tools for calculations of electronic structure of atoms, molecules and solids.
In 1939 M.I. Petrashen got her Ph.D. degree and simultaneously was invited by V.I. Smirnov to lecture at the University. From then on all her life turned out to be connected with two Divisions of the Physics Department: Mathematical Division (V.I. Smirnov) and Quantum Mechanics Division (V.A. Fock). Undoubtedly this fact determined her scientific interests as well as the circle of her friends. In 1940 V.A. Fock, M.G. Veselov and M.I. Petrashen developed a new method of incomplete separation of variables in the theory of many-electron systems, which subsequently became one of the basic methods for describing the electronic correlations. The equations obtained in the paper are presently known in scientific literature as Fock-Veselov-Petrashen equations.
After the most terrible winter of 1941-1942 during which Maria Ivanovna stayed in Leningrad, she was evacuated to Elabuga and participated in solution of various significant and urgent problems required by the defense industry. Afterwards this activity was rewarded by the Soviet Government.
Upon her return to Leningrad after the war, M.I. Petrashen continued research in the field of quantum mechanics of atoms. Slightly later she began fundamental investigation of electronic structure of solids, mainly of dielectrics. In order to solve this extremely complicated problem she has successfully applied group-theoretical methods. As a result of this work, a book was written (M.I. Petrashen, E.D. Trifonov, "Application of Group Theory in Quantum Mechanics"). This book became a classical manual for many generations of students.
One should especially mention an outstanding pedagogical skill of Maria Ivanovna Petrashen. Her lectures were extremely clear and laconic. She had a rare gift of attracting young people, of awakening their interest in science and stimulating them to think and act on their's own. She never overwhelmed students with her authority but always encouraged their scientific activity. Everybody who was lucky to associate and to work with Maria Ivanovna Petrashen will always remember her as an outstanding scientist and talented teacher, a benevolent friend always ready to come to help, a strong-willed personality of extreme honesty and modesty.