Publications

We calculate the spectra, electric dipole transition rates and isotope shifts of the super heavy elements Ds (Z=110), Rg (Z=111) and Cn (Z=112) and their ions. These calculations were performed using a recently developed, efficient version of the ab initio configuration interaction combined with perturbation theory to treat distant effects. The successive ionization potentials of the three elements are also calculated and compared to lighter elements.

We use recently developed efficient versions of the configuration interaction method to perform ab initio calculations of the spectra of superheavy elements seaborgium (Sg, Z=106), bohrium (Bh, Z=107), hassium (Hs, Z=108), and meitnerium (Mt, Z=109). We calculate energy levels, ionization potentials, isotope shifts, and electric dipole transition amplitudes. Comparison with lighter analogs reveals significant differences caused by strong relativistic effects in superheavy elements. Very large spin-orbit interaction distinguishes subshells containing orbitals with a definite total electron angular momentum j. This effect replaces Hund's rule holding for lighter elements.

We calculate the spectrum and allowed E1 transitions of the superheavy element Og (Z=118). A combination of configuration interaction and perturbation theory is used [Dzuba et al., Phys. Rev. A 95, 012503 (2017)]. The spectrum of lighter analog Rn i is also calculated and compared to experiment with good agreement.

The existence of permanent electric dipole moments (EDMs) and magnetic quadrupole moments (MQMs) violate both time reversal invariance (T) and parity (P). Following the CPT theorem they also violate combined CP symmetry. Nuclear EDMs are completely screened in atoms and molecules while interaction between electrons and MQMs creates atomic and molecular EDMs which can be measured and used to test CP-violation theories. Nuclear MQMs are produced by the nucleon-nucleon T, P-odd interaction and by nucleon EDMs. In this work we study the effect of enhancement of the nuclear MQMs due to the nuclear quadrupole deformation. Using the Nilsson model we calculate the nuclear MQMs for deformed nuclei of experimental interest and the resultant MQM energy shift in diatomic molecules of experimental interest ¹⁷³YbF, ^177,179HfF⁺, ¹⁸¹TaN, ¹⁸¹TaO⁺, ²²⁹ThO and ²²⁹ThF⁺.

Atomic spectra and other properties of superheavy element dubnium (Db, Z=105) are calculated using recently developed method combining configuration interaction with perturbation theory [the CIPT method, V. A. Dzuba, J. C. Berengut, C. Harabati, and V. V. Flambaum, Phys. Rev. A 95, 012503 (2017)]. These include energy levels for low-lying states of Db and Db II, electric dipole transition amplitudes between the ground state and low-lying states of opposite parity, isotope shift for these transitions, and the ionization potential of Db. Similar calculations for Ta, which is a lighter analog of Db, are performed to control the accuracy of the calculations.

We introduce the weak quadrupole moment (WQM) of nuclei, related to the quadrupole distribution of the weak charge in the nucleus. The WQM produces a tensor weak interaction between the nucleus and electrons and can be observed in atomic and molecular experiments measuring parity nonconservation. The dominating contribution to the weak quadrupole is given by the quadrupole moment of the neutron distribution, therefore, corresponding experiments should allow one to measure the neutron quadrupoles. Using the deformed oscillator model and the Schmidt model we calculate the quadrupole distributions of neutrons, Q_n , the WQMs, Q_W⁽²⁾, and the Lorentz invariance violating energy shifts in ⁹Be, ²¹Ne, ²⁷Al, ¹³¹Xe, ¹³³Cs, ¹⁵¹Eu, ¹⁵³Eu, ¹⁶³Dy, ¹⁶⁷Er, ¹⁷³Yb, ¹⁷⁷Hf, ¹⁷⁹Hf, ¹⁸¹Ta, ²⁰¹Hg and ²²⁹Th.

Here we calculate the electron transmission phase through a quantum point contact (QPC). The QPC is considered in the saddle-point approximation in the single-electron picture. We show that when the electron energy is close to the height of the potential barrier, the transmission phase depends linearly on the energy. The coefficient in the linear dependence is logarithmically enhanced by the ratio of the height over the curvature of the barrier potential. We compare the calculated transmission phase with the first experimental measurements of the phase.