Igor V. Abarenkov
(13.05.1931 - 06.03.2023)
Professor, Doctor of Physical and Mathematical Sciences
Honored Scientist of the Russian Federation
Honorary Professor of St. Petersburg State University
Fellow of the Institute of Physics (UK)
Igor Vasilyevich Abarenkov was born on May 13, 1931 in Leningrad. His parents Ekaterina Alexandrovna and Vasily Vasilyevich were military chemical engineers. In 1932, his father moved to Moscow, while Igor Vasilyevich and his mother remained in Leningrad. Until the age of 8, Igor Vasilyevich was brought up by his grandmother Nina Alexandrovna, who had a huge influence on the formation of his character.
When the war with Germany began in 1941, Igor Vasilyevich among other children was sent to Chelyabinsk region near Ural mountains. It was a harsh and hungry time. In 1943, his father, at that time a lieutenant general of artillery and one of the developers of the legendary Katyusha rocket system, located Igor Vasilyevich and took the boy to Moscow. Later on, Igor Vasilyevich recalled how he lived in his father's office but the most vivid impression of his childhood was the Victory Parade in 1945, which he watched with his father on Red Square.
After the war, Igor Vasilyevich returned to Leningrad, to the same apartment on Tchaikovsky Street. In 1949, after graduating from high school, he entered the Department of Physics of Leningrad State University, choosing to specialize in theoretical physics. At that time, the Division of Theoretical Physics was headed by Vladimir Alexandrovich Fock. Professor Maria Ivanovna Petrashen, a student and closest collaborator of V.A. Fock, became a supervisor and teacher for Igor Vasilyevich. Under her leadership, already in the third year, Igor Vasilyevich began his research activity. In 1954, his first research paper was published (together with M.I. Petrashen), in which a semi-empirical method for calculating the oscillator strengths for optical transitions in atoms was formulated. After graduating with honors in 1954, Igor Vasilyevich entered the graduate school.
In 1959, he successfully defended his Ph.D. thesis "Quantum-mechanical calculation of the optical properties of F-centers in alkali halide crystals in the point lattice approximation".
In 1962, Igor Vasilyevich went on a one-year internship at the Cavendish Laboratory of Cambridge University (England), where at that time a company of very strong young scientists gathered: Volker Heine, Lu Sham, Neil Ashcroft, Alexander Animalu.
It must be said that Igor' Vasilyevich came to England, already having a significant scientific background in the theory of pseudopotential. In particular, the article (together with V.F. Bratsev) "The Method of Effective Potential" was already prepared for publication and eventually published in Lithuanian Physical Collection journal in the first quarter of 1963.
In the course of scientific discussions with Volker Heine, Igor Vasilyevich came up with the idea to replace the true potential with a model semilocal pseudopotential. This is how the model pseudopotential was born, which soon after that began to be called the Heine-Abarenkov model pseudopotential in the scientific literature, monographs and university textbooks on physics and solid state theory.
With these works, a collaboration with Volker Heine began that developed into a friendship. This visit to England was the beginning of Igor Vasilyevich's long-term work on the development and application of the pseudopotential theory, which was reflected in a large series of published articles and his Doctor of Science thesis "The Method of Model Potential in the Theory of Electron Structure of Solid State Structure" defended in 1976. At the time of the thesis defence, the Heine-Abarenkov potential was 12 years old, and Igor Vasilyevich by that time had gained a wide recognition and fame among the world scientific community.
Igor' Vasilyevich's contribution to the theory of pseudopotential is not limited to the now classical works on the model pseudopotential. His ideas on the theory of pseudopotential were further elaborated in the method of variable potential proposed and developed by him for calculating the wave functions of ions in a crystal, applied to the calculation of the electronic structure of a bulk MgO crystal and its surface (together with I.M. Antonova), as well as in its works on the construction of separable pseudopotentials for modeling covalent chemical bonds (together with I.I. Tupitsyn).
The area of research interests of Igor Vasilyevich was quite wide, diverse and far from being exhausted by various aspects of the theory of pseudopotential and its applications. Igor Vasilyevich also made a significant contribution to the development of various problems in the quantum theory of atoms, molecules, solids, and impurity centers in wide-gap dielectrics. He developed a microscopic theory of two- and three-particle interactions in ionic crystals, which was generalization of the classic works of Per-Olov Lowdin on the theory of cohesion forces in ionic crystals, he proposed the concept of a glass-forming quasi-complex and a semi-empirical method for calculating the electronic structure of glass, and published works on the Wigner crystal and the study of the nature RVB (Resonating-Valence-Bond) states. He also took part in applied works in co-operation with experimentalists, among which the work "Fermi surface and thermopower of copper" (together with M.V. Vedernikov) stands out.
The works of I.V. Abarenkov of the last decade were devoted to the development of the method of embedding potential proposed by him earlier, which was taken as the basis for the modern embedding theory of crystal developed by him in recent years (the theory of "diving" of a cluster in a crystal), which opens up prospects for consistently taking into account correlation effects in crystals.
Being clearly influenced by his teachers V.A. Fock and M.I. Petrashen, Igor Vasilyevich showed a great interest in mathematical aspects of the theory, which was reflected in his works on the study of nonlinear properties of the of the Hartree-Fock equations for model Hamiltonians, a series of papers on the study of the nature of the antiferromagnetic state for model systems, as well as in articles on the basis overcrowding of the OPW (orthogonalised plane wave) method in solid state theory, the complete system of functions in the Heitler-London method, the crystal potential and the summation of divergent series (together with I.I. Tupitsyn), the cluster decomposition for the density matrix of an ionic crystal (in collaboration with I.M.Antonova), on the spin structure of the reduced density matrix of the first order and spin-polarised states (together with S.N. Zaguliaev). In his works Igor Vasilyevich also widely used numerical methods. As Igor Vasilyevich himself said, he was introduced to working on computers by V.F. Brattsev, a mathematician by education, back in those days when programming was done in computer codes.
Many studies of I.V. Abarenkov were held in cooperation with scientists from the world's leading research centers: the Cavendish Laboratory in Cambridge and University College London (UCL). I.V. Abarenkov twice became a laureate of the P.L. Kapitza scholarship of the Royal Society of Great Britain, and in 2000 he was elected a full member of the British Physical Society.
The scientific school created by I.V. Abarenkov continues the traditions laid down in theoretical physics by academician V.A. Fock and Professor M.I. Petrashen. Many of those who are not direct students of I.V. Abarenkov, but with whom he was associated for many years of scientific and human communication and friendship, also consider themselves as his students, and I.V. Abarenkov himself their Teacher.
Igor Vasilyevich is the author of a large number of research papers, two monographs and a number of textbooks on theoretical physics. In 1964, he developed an original course in quantum mechanics, which he taught to the students of the University. In addition, over the years, Igor Vasilyevich lectured on theoretical mechanics, quantum chemistry, solid state physics and a number of special courses on solid state theory at the Physics and Chemistry Departments. Igor Vasilyevich was an excellent lecturer. According to the reviews of colleagues and students, his lectures were distinguished by logical rigor and clarity of presentation, and were always emotionally colored. According to student surveys, Igor Vasilyevich was recognised as the best lecturer of the Physics Department of SPbSU, although he was a strict teacher and it was difficult to pass his exams.
For 30 years (1976-2006), taking the baton from the hands of Maria Ivanovna Petrashen, I.V. Abarenkov led the famous citywide scientific seminar on the theory of solid state in Leningrad Branch of the Mathematical Institute, which he himself called, in memory of his Teacher, the seminar of M.I. Petrashen.
Research and teaching achievements of Igor Vasilyevich are marked by numerous encouragements and awards. In 2016, he was awarded the V.A. Fock Prize of the Russian Academy of Sciences for his work "The pseudopotential method in the theory of the electronic structure of metals and dielectrics".
Igor Vasilyevich devoted almost seventy years to Leningrad / St. Petersburg State University, having gone from a student to a professor, head of the Chair of Quantum Mechanics, honorary professor of St. Petersburg State University. While studying at the university, Igor Vasilyevich actively participated in the social life of the faculty, tried to help and helped when anybody turned to him for help.
The passing of Igor Vasilyevich is irreparable. However, he will forever remain in our memory as a man of rare charm and goodwill, amazing openness and ease of communication.