arXiv subjects

Rytis Jursenas

Publications and source records attributed to Rytis Jursenas.

22 records · Page 2Linked to original sources

arXiv2012

On the three-body Schrödinger equation with decaying potentials

The three-body Schrödinger operator in the space of square integrable functions is found to be a certain extension of operators which generate the exponential unitary group containing a subgroup with nilpotent Lie algebra of length $κ+1$, $κ=0,1,...$ As a result, the solutions to the three-body Schrödinger equation with decaying potentials are shown to exist in the commutator subalgebras. For the Coulomb three-body system, it turns out that the task is to solve - in these subalgebras - the radial Schrödinger equation in three dimensions with the inverse power potential of the form $r^{-κ-1}$. As an application to Coulombic system, analytic solutions for some lower bound states are presented. Under conditions pertinent to the three-unit-charge system, obtained solutions, with $κ=0$, are reduced to the well-known eigenvalues of bound states at threshold.

quant-ph↗

arXiv2010

Application of symbolic programming for atomic many-body theory

In the present paper by using Mathematica system a symbolic programming method for generation of the expressions of the expansion terms of atomic stationary perturbation theory (PT) is presented. For this purpose, the package named as NCoperators was developed. In producing the PT terms, this package accommodates the features of the Rayleigh-Schrödinger perturbation theory (RSPT), the second quantization method (SQR) and angular momentum theory (AMT). The package was built in such a way that it could be applicable in various areas of theoretical atomic spectroscopy. Many functions of the NCoperators can be easily adapted for users to their own demand by easily transforming the functions developed. The package gives a possibility of generating formulas in traditional output form. For some quantities the expressions obtained in Mathematica can be converted into C code. Although the NCoperators package was developed for Unix OS, it can be easily adopted for other OSs if some of the parameters to be changed.

physics.atom-ph↗

arXiv2010

Coupled tensorial form for atomic relativistic two-particle operator given in second quantization representation

General formulas of the two-electron operator representing either atomic or effective interactions are given in a coupled tensorial form in relativistic approximation. The alternatives of using uncoupled, coupled and antisymmetric two-electron wave functions in constructing coupled tensorial form of the operator are studied. The second quantization technique is used. The considered operator acts in the space of states of open-subshell atoms.

physics.atom-ph↗

arXiv2010

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.

physics.atom-ph↗