ABSTRACT:The generalized relativistic effective core potential GRECP method is analyzed from theoretical and computational points of view. The Hamiltonian in the frozen-core approximation is compared with the Hamiltonian containing the GRECP operator. It is demonstrated that the GRECP operator can be derived from rather natural physical grounds and the procedure of the GRECP generation can be justified theoretically. The accuracy of the RECP approximations in the simulation of the interactions and densities in the valence and outer-core regions is analyzed. The reliability of the simulation of the interaction with the inner-core electrons removed from the calculations with the GRECP is also studied. The importance of additional nonlocal terms both with the potentials for the outer-core pseudospinors and with the potentials depending on the occupation numbers of the outermost core shells in the expression for the GRECP operator is demonstrated in calculations on the Ag, Ba, Hg, Tl, and U atoms. The difference between the outer core and valence potentials was investigated. It is shown that in the valence region the two-component pseudospinors coincide with the large components of four-component spinors in calculations for the same configuration states with a very high accuracy. Problems of Gaussian approximation caused by rather singular shapes of the potentials are considered. To attain a required high accuracy of approximation of the numerical potentials by Gaussians, serious additional efforts were undertaken.

No abstract

We report results of ab initio calculation of the spin-rotational Hamiltonian parameters including P -and P, T -odd terms for the BaF molecule. The ground state wave function of BaF molecule is found with the help of the Relativistic Effective Core Potential method followed by the restoration of molecular four-component spinors in the core region of barium in the framework of a non-variational procedure. Core polarization effects are included with the help of the atomic Many Body Perturbation Theory for Barium atom. For the hyperfine constants the accuracy of this method is about 5-10%. 31.25.Nj, 31.90.+s, 32.80.Ys, 33.15.Pw Typeset using REVT E X 1

Relativistic ab initio calculations have been performed to assess the suitability of RaF for experimental search of P− and T,P−violating interactions. The parameters of P− and T,P−odd terms of the spin-rotational Hamiltonian have been calculated for the 2 Σ electronic ground state of 223 RaF molecule. They include the Wa parameter, which is critical in experimental search for nuclear anapole moment and the parameters W d and WSP required to obtain restrictions on the electric dipole moment of the electron and T,P−odd scalar−pseudoscalar interactions, respectively. The parameter X corresponding to the "volume effect" in the T,P−odd interaction of the 223 Ra nuclear Schiff moment with electronic shells of RaF has also been computed. Spectroscopic and hyperfine structure constants for 223 RaF and 223 Ra + have been computed as well, demonstrating the accuracy of the methods employed.