About Oleg P. Charkin
Before setting out the main stages of the scientific activity of Oleg Petrovich Charkin, it is necessary to at least briefly recall the formation of quantum chemistry in the USSR. Although this scientific area is now strongly associated with the United States, Soviet academician V.A. Fock is directly related to its emergence (the Hartree-Fock method, which is the foundation of modern quantum chemistry). Under his leadership, M.M. Mestechkin, M.G. Veselov, M.I. Petrashen et al. developed a mathematical apparatus for solving various problems of quantum chemistry, primarily for the interpretation of the spectra of alternant hydrocarbons. Quantum chemical groups arose in other centers, in particular at the chemical department of the Moscow State University under the guidance of N.F. Stepanov, at the Moscow Institute of Chemical Technology (Acad. Y.K. Syrkin), in Institute of General and Inorganic Chemistry RAS (Prof. M.E. Dyatkin).
The beginning of the scientific activity of Oleg P. Charkin was closely connected with the last two groups. Among their main priorities was the explanation of the structure and properties of such inorganic compounds whose structure cannot be understood from the point of view of classical concepts of valence and chemical bonds, such as inert gas halides and interhalogens (for example, XeF2, XeF4, XeF6, ClF3, ClF5) , borohydrides, aluminum hydrides, mutual influence of ligands in complex compounds, etc. However, quantum chemical methods available at that time, based on semi-empirical approximations, gave satisfactory results only for aromatic therefore, to model more complex systems, it was necessary to develop new approaches based on the zero differential overlap approximation. Such work was carried out in a number of centers, including in the group led by Y.K. Syrkina and M.E. Dyatkina, which included and Oleg P. Charkin. The developed approach was successfully applied to explain the structure of the halides of inert gases and interhalogens, but in general has not proved to be universal. However, during this period, based on the development of both mathematical approaches and the improvement of computer technology, computer programs began to be created that implement the non-empirical method of Hartree-Fock-Rutan, and Oleg P. Charkin began to actively implement this approach in the quantum chemical group he created, and then in the laboratory in the Institute of New Chemical Problems USSR Academy of Sciences (Chernogolovka). A significant role in the successful implementation of this project was played by Charkin’s organizational skills. The first one is the ability to establish working contacts with foreign colleagues who have the appropriate calculation base, to find powerful enough computer centers suitable for carrying out non-empirical calculations and to organize cooperation with them. Another very important factor is the ability to organize the work of the laboratory so that, in parallel with the modeling, there was a continuous process of training its staff. For this purpose, Abstract Journal Chemistry was annually discharged to the laboratory. All members of the laboratory reviewed it and briefly reported at weekly working seminars about the most interesting works, both on the methods and techniques of calculations, and on the objects under study. In addition, each of the employees briefly described both the obtained intermediate results and the problems encountered at this stage of work. As a rule, as a result of collective discussion, it was possible to choose the most effective ways to move forward. Such seminars contributed to the rapid exchange of experience and knowledge among staff and their mutual learning.
The work of the laboratory was carried out in such areas as calculations of potential surfaces of penetration reactions in a bond, intramolecular rearrangements, structurally non-rigid molecules, including complex metal hydrides, borohydrides, carboranes, inversion non-rigidity, pseudo-rotation in electron-excess compounds, frame compounds, etc. Unfortunately, with the collapse of the USSR and the cessation of the work of large computer centers, the work of the laboratory practically stopped, and the majority of young and middle-aged laboratory workers went to various foreign research centers. Thanks to the good preparation, almost everyone got good positions, mainly in the USA (A.M. Mebel – at the University of Florida, A.I. Boldyrev – at the University of Salt Lake City, D.G. Musaev – at Emory University, V.G. Zakzhevsky to the GAUSSIAN company, G. Chaban – at NASA. Unfortunately, in Russia, except for Oleg P. Charkin, only three former laboratory staff members remained, and it was disbanded. Nevertheless, the remaining employees in Russia continued to work actively, mainly in collaboration with fellow Taiwanese and American colleagues by Charkin’s employees. Such contacts allowed us to use modern quantum chemical programs and the resources of powerful foreign computer centers, with which we had big problems from 1991 to 2001. However, gradually our situation began to improve both in terms of calculation programs, and computational facilities, and now actively working groups have appeared in a number of centers – at our institute in Chernogolovka, in Moscow (Moscow State University, Center for Photochemistry of the Russian Academy of Sciences, Institute of General and Inorganic Chemistry RAS), in Ivanovo, in Irkutsk. Let’s hope that this trend will continue, and quantum chemistry will develop in our country.