# Alexander OleynichenkoPetersburg Nuclear Physics Institute | PNPI

Alexander Oleynichenko

Doctor of Philosophy

relativistic multireference coupled cluster theory, pseudopotentials, heavy atoms & molecules

## About

48

Publications

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231

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Citations since 2017

Introduction

relativistic multireference coupled cluster theory

## Publications

Publications (48)

Generalized relativistic pseudopotentials (GRPP) of atomic cores implying the use of different potentials for atomic electronic shells with different principal quantum numbers give rise to accurate and reliable relativistic electronic structure models of atoms, molecules, clusters, and solids. These models readily incorporate the effects of Breit e...

Generalized relativistic pseudopotentials (GRPP) of atomic cores implying the use of different potentials for atomic electronic shells with different principal quantum numbers give rise to accurate and reliable relativistic electronic structure models of atoms, molecules, clusters, and solids. These models readily incorporate the effects of Breit e...

Table S1: Excitation energies derived from all-electron numerical SCF calculations for the states averaged over nonrelativistic configurations of the Th+ cation with DCB Hamiltonian and accounting for the finite nuclear size and QED effects. The contributions from various effects are the differences from the results of the all-electron numerical SC...

Supplementary materials:
Exponential parameters of the primitive Gaussian basis sets for Ra, Tl and Lu.

Four-component relativistic all-order multireference electron correlation approaches are the most accurate methods available for benchmark calculations of properties of heavy atoms and their compounds with complex (frequently quasi-degenerate) electronic shell structures. Benchmarking requires continued improvement of the relativistic Hamiltonian a...

A simple procedure to incorporate one‐loop quantum electrodynamic (QED) corrections into the generalized (Gatchina) nonlocal shape‐consistent relativistic pseudopotential model is described. The pseudopotentials for Lu, Tl, and Ra replacing only inner core shells (with principal quantum numbers n ≤ 3 for the two former elements and n ≤ 4 for the la...

A simple procedure to incorporate one-loop quantum electrodynamic (QED) corrections into the generalized (Gatchina) nonlocal shape-consistent relativistic pseudopotential model is described. The pseudopotentials for Lu, Tl, and Ra replacing only inner core shells (with principal quantum numbers n <= 3 for the two former elements and n <= 4 for the...

The successive ionization potentials (IPs) and electron affinities (EAs) for superheavy elements with 111 Z 114, namely, Rg, Cn, Nh, and Fl, are reexamined using the relativistic Fock-space coupled-cluster method with nonperturbative single (S), double (D), and triple (T) cluster amplitudes (FS-CCSDT). For most of the considered quantities, the tri...

The AcOH+ molecular ion is identified as a prospective system to search for CP-violation effects. According to our study AcOH+ belongs to the class of laser-coolable polyatomic molecular cations implying a large coherence time in the experiments to study symmetry-violating effects of fundamental interactions. We perform both nuclear and high-level...

We estimate the effect of the tensor parity nonconserving (PNC) interaction in the $^{181}$TaO$^+$ molecular cation. It can be used to probe the unknown quadrupole distribution of the neutrons inside the Ta nucleus. To this end, we evaluate the constant which characterizes this interaction using the relativistic Fock space coupled cluster theory fo...

The successive ionization potentials (IPs) and electron affinities (EAs) for superheavy elements with 111 <= Z <= 114, namely, Rg, Cn, Nh, and Fl are reexamined using the relativistic Fock-space coupled-cluster method with nonperturbative single (S), double (D), and triple (T) cluster amplitudes (FS-CCSDT). For the most of considered quantities, th...

We estimate the effect of the tensor parity nonconserving (PNC) interaction in the 181TaO⁺ molecular cation. It can be used to probe the unknown quadrupole distribution of the neutrons inside the Ta nucleus. To this end, we evaluate the constant which characterizes this interaction using the relativistic Fock space coupled cluster theory for electr...

Laser-induced fluorescence spectra of the c3Σ+(vc,Jc=Nc)→a3Σ+(va,Na=Jc±1) transitions excited from the ground X1Σ+ state of 39K133Cs molecule were recorded with Fourier-transform spectrometer IFS125-HR (Bruker) at the highest achievable spectral resolution of 0.0063 cm−1. Systematic study of the hyperfine structure (HFS) of the a3Σ+ state for level...

Laser-induced fluorescence spectra of the $c^3\Sigma^+(v_{c},J_{c}=N_{c})\rightarrow a^3\Sigma^+(v_{a},N_{a} = J_{c} \pm 1)$ transitions excited from the ground $X^1\Sigma^+$ state of $^{39}$K$^{133}$Cs molecule were recorded with Fourier-transform spectrometer IFS125-HR (Bruker) at the highest achievable spectral resolution of 0.0063 cm${}^{-1}$....

Relativistic effective atomic configurations of superheavy elements Cn, Nh and Fl and their lighter homologues (Hg, Tl and Pb) in their simple compounds with fluorine and oxygen are determined using the analysis of local properties of molecular Kohn-Sham density matrices in the vicinity of heavy nuclei. The difference in populations of atomic spino...

A new iterative version of population projection analysis is formulated and applied to determine relativistic effective atomic configurations of superheavy elements Cn and Fl and their lighter homologues (Hg and Pb) in the molecules of their fluorides and oxides. The dependence of the computed populations on the initial reference atomic spinors is...

The AcOH+ molecular ion is identified as a prospective system to search for CP-violation effects. According to our study AcOH+ belongs to the class of laser-coolable polyatomic molecular cations implying the large coherence time in the experiments to study symmetry violating effects of fundamental interactions. We perform both nuclear and high leve...

The changes in the mean-square charge radius (relative to 209 Bi), magnetic dipole, and electric quadrupole moments of 187;188;189;191 Bi were measured using the in-source resonance-ionization spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in 187;188;189 Bi g , manifested by a sharp radius increase for the ground sta...

We report the value of the electric quadrupole moment of Bi209 extracted from the atomic data. For this, we performed electronic structure calculations for the ground S3/2o4 and excited P3/2o2 states of atomic Bi using the Dirac-Coulomb-Breit Hamiltonian and the Fock space coupled-cluster method with single, double, and full triple amplitudes for t...

The Ti:Saphire laser operated within 13800 - 11800 cm−1 range was used to excite the c3Σ+ state of KCs molecule directly from the ground X1Σ+ state. The laser-induced fluorescence (LIF) spectra of the c3Σ+→a3Σ+ transition were recorded with Fourier-transform spectrometer within 8000 to 10000 cm−1 range. Overall 673 rovibronic term values belonging...

The electron affinity (EA) of the superheavy element Og is calculated by the use of the relativistic Fock-space coupled cluster (FSCC) and configuration interaction methods. The FSCC cluster operator expansion includes single, double, and triple excitations treated in a nonperturbative manner. The Gaunt and retardation electron-electron interaction...

The Ti:Saphire laser operated within 13800 - 11800 cm$^{-1}$ range was used to excite the $c^3\Sigma^+$ state of KCs molecule directly from the ground $X^1\Sigma^+$ state. The laser-induced fluorescence (LIF) spectra of the $c^3\Sigma^+ \rightarrow a^3\Sigma^+$ transition were recorded with Fourier-transform spectrometer within 8000 to 10000 cm$^{-...

The YbOH triatomic molecule can be efficiently used to measure the electron electric dipole moment, which violates time-reversal (T) and spatial parity (P) symmetries of fundamental interactions [Kozyryev and Hutzler, Phys. Rev. Lett. 119, 133002 (2017)]. We study another mechanism of the T, P-violation in the YbOH molecule—the electron–electron in...

We report the value of the electric quadrupole moment of $^{209}$Bi extracted from the atomic data. For this, we performed electronic structure calculations for the ground $^4S^o_{3/2}$ and excited $^2P^o_{3/2}$ states of atomic Bi using the Dirac-Coulomb-Breit Hamiltonian and the Fock space coupled cluster method with single, double, and full trip...

The electron affinity (EA) of superheavy element Og is calculated by the use of the relativistic Fock-space coupled cluster (FSCC) and configuration interaction methods. The FSCC cluster operator expansion included single, double, and triple excitations treated in a non-perturbative manner. The Gaunt and retardation electron-electron interactions a...

The YbOH triatomic molecule can be efficiently used to measure the electron electric dipole moment, which violates time-reversal (T) and spatial parity (P) symmetries of fundamental interactions [I. Kozyryev, N.R. Hutzler, Phys. Rev. Lett. 119, 133002 (2017)]. We study another mechanism of the T,P-violation in the YbOH molecule - the electron-elect...

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...

The spin-forbidden a3Π−X1Σ+, a′3Σ+−X1Σ+ and spin-allowed A1Π−X1Σ+ electronic transitions dipole moments of carbon monoxide have been ab initio studied in the framework of multi-reference Fock space coupled cluster method combined with the finite-field approach and the generalized relativistic pseudo-potential model for the effective introducing the...

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...

Modern challenges arising in the fields of theoretical and experimental physics require new powerful tools for high-precision electronic structure modelling; one of the most perspective tools is the relativistic Fock space coupled cluster method (FS-RCC). Here we present a new extensible implementation of the FS-RCC method designed for modern paral...

Reliable information on transition matrix elements of various property operators between molecular electronic states is of crucial importance for predicting spectroscopic, electric, magnetic and radiative properties of molecules. The finite-field technique is a simple and rather accurate tool for evaluating transition matrix elements of first-order...

We observed the A1Σ+∼b3Π→a3Σ+/X1Σ+ laser-induced fluorescence (LIF) of the RbCs molecule excited from the ground X1Σ+ state by the Ti:Sapphire laser. The LIF spectra from the common perturbed levels of the singlet-triplet A ∼ b complex was recorded by the Fourier-transform (FT) spectrometer with the instrumental resolution of 0.03 cm−1. The relativ...

Reliable information on transition matrix elements of various property operators between molecular electronic states is of crucial importance for predicting spectroscopic, electric, magnetic and radiative properties of molecules. The finite-field technique is a simple and rather accurate tool for evaluating transition matrix elements of first-order...

The intercombination $a^3\Pi - X^1\Sigma^+$ Cameron system of carbon monoxide has been computationally studied in the framework of multi-reference Fock space coupled cluster method with the use of generalized relativistic pseudopotential model for the effective introducing the relativity in all-electron correlation treatment. The extremely weak $a^...

We observed the $A^1\Sigma^+\sim b^3\Pi\to a^3\Sigma^+/X^1\Sigma^+$ laser-induced fluorescence (LIF) spectra of the RbCs molecule excited from the ground $X^1\Sigma^+$ state by the Ti:Sapphire laser. The LIF radiation from the common perturbed levels of the singlet-triplet $A\sim b$ complex was recorded by the Fourier-transform (FT) spectrometer wi...

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 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...

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...

Modern challenges arising in the fields of theoretical and experimental physics require new powerful tools for high-precision electronic structure modelling; one of the most perspective tools is the relativistic Fock space coupled cluster method (FS-RCC). Here we present a new extensible implementation of the FS-RCC method designed for modern paral...

High-level procedures (MP2, CCSD, CCSD(T)) and reliable experimental data have been used to assess the performance of a variety of exchange-correlation functionals for the calculation of structures and energies of small models of thiolate-protected gold clusters. Clusters represent rather complicated objects for examination, therefore the simple mo...

The determination of the matrix elements of single-electron operators for the transitions between electronic states (primarily, the dipole moments of electron transitions) is one of the critical problems in simulating the atomic and molecular spectra. In this study, the efficiency of a simple version of the finite-field method for calculating these...

Relativistic effective atomic configurations of superheavy elements Cn, Nh and Fl and their lighter homologues (Hg, Tl and Pb) in their simple compounds with fluorine and oxygen are determined using the analysis of local properties of molecular Kohn-Sham density matrices in the vicinity of heavy nuclei. The difference in populations of atomic spino...

The structures of [Au4(dpmp)2X2]²⁺clusters, where Х =–C≡CH,–СН3,–SCH3,–F,–Cl,–Br,–I, dpmp is bis((diphenylphosphino)methyl)(phenyl)phosphine, are calculated at the level of density functional theory with the PBE functional and a modified Dirac–Coulomb–Breit Hamiltonian in an all-electron basis set (Λ). Using the example of [Au4(dpmp)2(С≡CС6Н5)2]²⁺,...

A new iterative version of population projection analysis is formulated and applied to determine relativistic effective atomic configurations of superheavy elements Cn and Fl and their lighter homologues (Hg and Pb) in the molecules of their fluorides and oxides. The resulting configurations are completely independent of the initial choice of refer...