Irreducible tensor form of three-particle operator for open-shell atoms

The three-particle operator in a second quantized form is studied. The operator is transformed into irreducible tensor form. Possible coupling schemes, distinguished by the classes of symmetric group \mathrm{S_{6}}, are presented. Recoupling coefficients, which allow one to transform given scheme into another, are produced by using the angular momentum theory, combined with quasispin formalism. The classification of three-particle operator, which acts on n=1,2,...,6 open shells of equivalent electrons of atom, is considered. The procedure to construct three-particle matrix elements are examined

Development of algebraic techniques for the atomic open-shell MBPT(3)

The atomic third-order open-shell many-body perturbation theory is developed. Special attention is paid to the generation and algebraic analysis of terms of the wave operator and the effective Hamiltonian as well. Making use of occupation-number representation and intermediate normalization, the third-order deviations are worked out by employing a computational software program that embodies the generalized Bloch equation. We prove that in the most general case, the terms of effective interaction operator on the proposed complete model space are generated by not more than eight types of the $n$-body ($n\geq2$) parts of the wave operator. To compose the effective Hamiltonian matrix elements handily, the operators are written in irreducible tensor form. We present the reduction scheme in a versatile disposition form, thus it is suited for the coupled-cluster approach

The transformation of irreducible tensor operators under spherical functions

The irreducible tensor operators and their tensor products employing Racah algebra are studied. Transformation procedure of the coordinate system operators act on are introduced. The rotation matrices and their parametrization by the spherical coordinates of vector in the fixed and rotated coordinate systems are determined. A new way of calculation of the irreducible coupled tensor product matrix elements is suggested. As an example, the proposed technique is applied for the matrix element construction for two electrons in a field of a fixed nucleus.Comment: To appear in Int. J. Theor. Phy

Theoretical investigation of spectroscopic properties of W 27+

Analysis of energy levels and radiative transition probabilities for the W27+ ion is performed using multiconfiguration Dirac-Fock method. Configuration interaction strength has been used to determine the influence of correlation effects

Theoretical study of W27+ spectra in EBIT plasma

Corona modeling of spectral lines for the W27+ ion is performed. Energy levels and radiative transition probabilities are calculated using GRASP2K and FAC codes. Electron-impact excitation rates are studied in the distorted wave approximation and are taken proportional to the electric dipole line strengths

Theoretical study of W25+ spectra

Analysis of energy levels and radiative transition probabilities for W25+ ion is performed using multiconfiguration Dirac-Fock methodVilniaus universitetasVytauto Didžiojo universitetasŠvietimo akademij