ИСТИНА

At present, the only way to study stars and other astrophysical objects, their structure, and processes occurring within them is to study their spectra. Amazing examples of such celestial bodies are "white dwarf" stars. To understand the structure of the life cycle of stars, it is important to study their chemical composition at different stages of development. The literature provides a qualitative analysis of the chemical composition of white dwarfs [1]. It is reported that, in addition to light hydrogen and helium, their composition also contains a number of elements of the second period [2]. This work continues the study of modeling the electronic structure of atoms of the second period in strong magnetic fields. Current best approach to carry out such calculations today is the method based on the modification of the one-electron part of the electron Hamiltonian by introducing additional terms in the presence of a uniform magnetic field [3-4]. This method modifies the standard algorithms of quantum chemistry, the electron Hamiltonian contributions explicitly depend on the spin and orbital momentum of the electron. Thus, the matrices with which one has to work are already clearly not just self-adjoint, but also complex, and the spin-orbitals for electrons with different spin values can no longer have the same spatial parts. All this significantly slows down the calculation speed. In this work we proposed a method for calculating the electronic structure in the version of the UHF, UMP2 methods and the full CI method in the framework of a similar formalism, also the MCSCF method is considered. The elements of the II period were calculated; the pattern of changes in the orbital energy and composition of orbitals in the case of a successive increase in the value of the external magnetic to extreme values was studied. Separately, the energy contributions to various components of magnetic interactions are calculated and general regularities are revealed in the dependences of the energies of electronic levels on the external magnetic field on the parameters of the system under study. The author is grateful to the Russian Science Foundation for the financial support under Project 22-23-01180.