*Article* **Fock Expansion for Two-Electron Atoms: High-Order Angular Coefficients**

**Evgeny Z. Liverts 1,\* and Rajmund Krivec 2**

	- **\*** Correspondence: evgeny.liverts@mail.huji.ac.il

**Abstract:** The Fock expansion, which describes the properties of two-electron atoms near the nucleus, is studied. The angular Fock coefficients *ψ<sup>k</sup>*,*<sup>p</sup>*(*<sup>α</sup>*, *θ*) with the maximum possible value of subscript *p* are calculated on examples of the coefficients with 5 ≤ *k* ≤ 10. The presented technique makes it possible to calculate such angular coefficients for any arbitrarily large *k*. The mentioned coefficients being leading in the logarithmic power series representing the Fock expansion, they may be indispensable for the development of simple methods for calculating the helium-like electronic structure. The theoretical results obtained are verified by other suitable methods. The Wolfram Mathematica is used extensively.

**Keywords:** two-electron atom/ion; wave function; Fock expansion; angular coefficients; Wolfram Mathematica
