Ephraim Eliav | Tel Aviv University (original) (raw)

Papers by Ephraim Eliav

arXiv (Cornell University), Apr 26, 2023

The tiny-core generalized (Gatchina) relativistic pseudopotential (GRPP) model provides an accura... more The tiny-core generalized (Gatchina) relativistic pseudopotential (GRPP) model provides an accurate approximation for many-electron Hamiltonians of molecules containing heavy atoms, ensuring a proper description of the effects of non-Coulombian electron-electron interactions, electronic selfenergy and vacuum polarization. Combining this model with electron correlation treatment in the frames of the intermediate Hamiltonian Fock space coupled cluster theory employing incomplete main model spaces, one obtains a reliable and economical tool for excited state modeling. The performance of this method is assessed in applications to ab initio modeling of excited electronic states of the thorium monoxide molecule with term energies below 20 000 cm −1. Radiative lifetimes of excited states are estimated using truncated expansions of effective and metric operators in powers of cluster amplitudes.

Abstract: Potential functions of the ground and low excited states of Al2 are calculated by the r... more Abstract: Potential functions of the ground and low excited states of Al2 are calculated by the relativistic Fock-space coupled cluster method in the framework of the projected Dirac-Coulomb Hamiltonian. A moderate-size basis [16s11p3d3f/6s6p3d2f] is used. 3 Πu is confirmed as the ground state of the system. Its spin orbit splittings are reproduced well, with the Λ = 1, 2 states lying 32.5 and 66.1 cm −1, respectively, above the Λ = 0 minimum (experimental values are 30.4 and 63.4 cm −1). The bond is somewhat too weak, with De 0.14 eV below experiment, Re too high by 0.08 ˚A, and ωe 21 cm −1 too low. It is speculated that the better agreement obtained in earlier calculations may be due to neglect of basis set superposition errors. The description of bonding in the molecule may be improved by the use of a better basis and the inclusion of more correlation by the intermediate Hamiltonian coupled cluster method, which makes it possible to handle larger P spaces and extend the potential...

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Physics Letters, 1966

Polyatomic polar molecules are promising systems for future experiments that search for violation... more Polyatomic polar molecules are promising systems for future experiments that search for violation of timereversal and parity symmetries due to their advantageous electronic and vibrational structure, which allows laser cooling, full polarization of the molecule, and reduction of systematic effects [Kozyryev and Hutzler, Phys. Rev. Lett. 119, 133002 (2017)]. In this paper we investigate the enhancement factor of the electric dipole moment of the electron (E eff) in the triatomic monohydroxide molecules BaOH and YbOH within the highaccuracy relativistic coupled cluster method. The recommended E eff values of the two systems are 6.42 ± 0.15 and 23.4 ± 1.0 GV/cm, respectively. We compare our results with similar calculations for the isoelectronic diatomic molecules BaF and YbF, which are currently used in the experimental search for P, T-odd effects in molecules. The E eff values prove to be very close, within about 1.5% difference in magnitude between the diatomic and the triatomic compounds. Thus, BaOH and YbOH have similar enhancements of the electron electric dipole moment, while benefiting from experimental advantages, and can serve as excellent candidates for next-generation experiments.

Journal of Chemical Physics, Oct 15, 2001

The intermediate Hamiltonian Fock-space coupled cluster method developed recently is applied to e... more The intermediate Hamiltonian Fock-space coupled cluster method developed recently is applied to excitations in the one-hole one-particle sector, taking xenon and radon atoms as test cases. Virtual orbitals are modified to yield better approximations to orbitals occupied in excited states. The usual Fock-space coupled cluster scheme diverges for these systems, but the intermediate Hamiltonian approach converges for large P spaces and yields excitation energies in very good agreement with experiment. The average error in the calculated values for the lowest excitation energies (about 20 for each atom) is 0.6%. Predictions are made for the unobserved 8s Rydberg states of Rn.

Encyclopedia of Inorganic and Bioinorganic Chemistry, Sep 14, 2018

Journal of Quantitative Spectroscopy & Radiative Transfer, Jul 1, 2021

Radium compounds have attracted recently considerable attention due to both development of experi... more Radium compounds have attracted recently considerable attention due to both development of experimental techniques for high-precision laser spectroscopy of molecules with short-lived nuclei and amenability of certain radium compounds for direct cooling with lasers. Currently, radium monofluoride (RaF) is one of the most studied molecules among the radium compounds, both theoretically and recently also experimentally. Complementary studies of further diatomic radium derivatives

Chemical Physics Letters, Oct 1, 2020

The four-component relativistic Fock space coupled cluster method is used to describe the magneti... more The four-component relativistic Fock space coupled cluster method is used to describe the magnetic hyperfine interaction in low-lying electronic states of the KCs molecule. Both diagonal and off-diagonal matrix elements as functions of the internuclear separation R are calculated within the finite-field scheme. The resulting matrix elements exhibit very weak dependence on R for the separations exceeding 8 Å, whereas in the vicinity of the ground-state equilibrium the deviation of molecular HFS matrix elements from the atomic values reaches 15%. The dependence of the computed HFS couplings on the level of core correlation treatment is discussed.

Physical review, Nov 29, 2022

Physical Review A, Feb 5, 2015

Calculations of the first and second ionization potentials and electron affinities of superheavy ... more Calculations of the first and second ionization potentials and electron affinities of superheavy elements 115-117 are presented. The calculations are performed in the framework of the Dirac-Coulomb Hamiltonian, and the results are corrected for the Breit and QED contributions. Correlation is treated by the relativistic coupled cluster approach with single, double, and perturbative triple excitations [CCSD(T)]. The same approach is used to calculate the ionization potentials and electron affinities of the lighter homologues, Bi, Po, and At. Comparison of the available experimental values for these atoms, namely, the first ionization potentials (IPs) of Bi, Po, and At and the second IP and EA of Bi, with our results shows excellent agreement, within a few hundredths of an eV, lending credence to our predictions for their superheavy homologues. High-accuracy predictions are also made for the second ionization potentials and electron affinities of Po and At, where no experiment is available.

Journal of Chemical Physics, Feb 15, 2001

The electronic level structure of eka-lead (element 114), the synthesis of which was reported las... more The electronic level structure of eka-lead (element 114), the synthesis of which was reported last year, is studied by the recently developed intermediate Hamiltonian Fock-space coupled-cluster method. Very large basis sets are used, with l up to 8, and 36 electron are correlated. The accuracy of the resulting transition energies is tested by applying the same method to Pb; calculated ionization potentials and excitation energies agree with experiment within a few hundredths of an eV, and similar accuracy is expected for the heavier element. Ionization potentials and excitation energies of E114 are considerably higher than for Pb, due to the relativistic stabilization of the 7s and 7p1/2 orbitals. This indicates that eka-lead will probably be more inert and less metallic than lead.

Журнал технической физики, 2018

Physical review, Dec 4, 2018

Symmetry, Jul 2, 2020

The Fock space relativistic coupled cluster method (FS-RCC) is one of the most promising tools of... more The Fock space relativistic coupled cluster method (FS-RCC) is one of the most promising tools of electronic structure modeling for atomic and molecular systems containing heavy nuclei. Until recently, capabilities of the FS-RCC method were severely restricted by the fact that only single and double excitations in the exponential parametrization of the wave operator were considered. We report the design and the first computer implementation of FS-RCC schemes with full and simplified non-perturbative account for triple excitations in the cluster operator. Numerical stability of the new computational scheme and thus its applicability to a wide variety of molecular electronic states is ensured using the dynamic shift technique combined with the extrapolation to zero-shift limit. Pilot applications to atomic (Tl, Pb) and molecular (TlH) systems reported in the paper indicate that the breakthrough in accuracy and predictive power of the electronic structure calculations for heavy-element compounds can be achieved. Moreover, the described approach can provide a firm basis for high-precision modeling of heavy molecular systems with several open shells, including actinide compounds.

Physical review, Apr 19, 2019

Molecular Physics, Jul 26, 2023

Physical review, Nov 17, 2021

We present high accuracy relativistic investigations of the spectrum of Lr, element 103, prompted... more We present high accuracy relativistic investigations of the spectrum of Lr, element 103, prompted by the planned optical spectroscopy experiments on this rare and short-lived atom. Reliable predictions of the transition lines are important for the planning and success of these challenging measurements. The relativistic coupled cluster approach (CCSD(T)) was used to calculate the energies of lowest excited states, while the combination of configuration interaction method with the many-body perturbation theory (CI+MBPT) was employed to address the higher-lying states and to obtain the transition strengths and the lifetimes of the levels of experimental interest. We performed similar calculations for Lu, the lighter homologue of Lr, where experimental data is available. For the lighter element, both the calculated energies and the Einstein coefficients are in excellent agreement with the previously measured values, confirming the accuracy of the performed calculations and the reliability of our predictions for Lr.

Recent Progress in Many-Body Theories, Dec 1, 2002