Bulletin of the American Physical Society
53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 67, Number 7
Monday–Friday, May 30–June 3 2022; Orlando, Florida
Session U04: Theory & Experiment: Spectroscopy Lifetimes & Oscillator StrengthsRecordings Available

Hide Abstracts 
Chair: Igor Savukov, LANL Room: Salon 3/4 
Thursday, June 2, 2022 2:00PM  2:12PM 
U04.00001: DopplerFree EIT Measurements of Isotope Shifts and Hyperfine Structure of the Potassium41 6s State Charles W Conover, Henry Pacheco Cachon, Ethan Springhorn We report Dopplerfree measurements and theoretical modeling of the 4s_{1/2}4p_{1/2}6s_{1/2} ladder using electromagnetically induced transparency (EIT). Using the acquired spectra we have measured the hyperfine splittings and isotope shift of the 6s state of potassium 41, which has not previously been reported. In the experiments the probe laser is locked to the to one of the 4s_{1/2}4p_{1/2} hyperfine transitions, while the coupling laser is scanned over the 4p_{1/2}6s_{1/2} transition. EIT was measured in a magnetically shielded warm vapor cell. The spectra are complicated by the relatively small hyperfine splitting in the 4p_{1/2 }state. We have explored the effect of relative polarizations of the probe and coupling lasers on the spectra both experimentally and with a multilevel theoretical model including magnetic sublevels. 
Thursday, June 2, 2022 2:12PM  2:24PM 
U04.00002: Fourlevel, all infrared, Dopplerfree Rydberg EIT in rubidium Brielle E Anderson, Donald P Fahey, Paul Kunz, David Meyer, Kevin C Cox Fourlevel, threephoton ladder Rydberg EIT has several potential advantages over the more popular twophoton Rydberg EIT in its applications to field sensing and nonclassical photon state generation. For example, in warm vapors, Dopplerfree alignments leading to zerovelocity spin waves or expanded velocity class inclusion are possible with threephoton EIT. We present experiments in warm vapors using an allinfrared scheme which include collinear configurations of the incoming lasers and a Dopplerfree configuration where the incoming beams’ wavevectors sum vectorially to zero. We show that numerical simulations match the qualitative features of the experimental configurations and that there are regimes where the Dopplerfree configuration may lead to improved sensitivity over collinear configurations. 
Thursday, June 2, 2022 2:24PM  2:36PM 
U04.00003: Solving for manybody stationary states using the Geminal Density Matrix Nicholas Cox The ground state energy of an arbitrary manyelectron system can be calculated by minimizing its total energy as a functional of the twobody reduced density matrix (2RDM). Such a minimization yields exact results only if the 2RDM is sufficiently constrained so that it corresponds to a valid manybody wave function. Despite significant progress over the last few decades, a complete set of these socalled Nrepresentability constraints has not been determined. This work approaches the problem by expanding the 2RDM in a complete set of twoelectron eigenstates and analyzing the matrix formed by the expansion coefficients. This matrix, which we call the geminal density matrix (GDM), is found to evolve unitarily in time by the LiouvilleVon Neumann equation. By studying the time evolution induced by a Hamiltonian that slowly switches on the Coulomb interaction, we show by the adiabatic theorem that matrices representing eigenstates of a noninteracting system can be evolved into those for a system with electronelectron interactions in a manner which preserves Nrepresentability. 
Thursday, June 2, 2022 2:36PM  2:48PM 
U04.00004: LongRange Rydberg States of Sr_{2}^{+} Teri Price, Chris H Greene Longrange diatomic Rydberg molecules with charged atomic cores have potential application in quantum computing, and there has recently been considerable interest in these types of systems. In this work, highlying longrange Rydberg states of spinpolarized Sr_{2}^{+} are presented. The electronic spectra were computed using an analytical approach involving a local frame transformation developed in a previous work, in which a scattering Kmatrix for collisions of the Rydberg electron with the charged cores is determined from states of H_{2}^{+} and experimental quantum defects for Sr. A formalism for determining dipole matrix elements between highlying states of Sr_{2}^{+} and the 5s5p state of Sr is presented. This formalism assumes the Sr atoms are each trapped in an optical tweezer, with a normal mode analysis used to compute the rovibrational overlap integral. Some bound states of Sr_{2}^{+} in this regime that could be experimentally observed are identified. 
Thursday, June 2, 2022 2:48PM  3:00PM 
U04.00005: Further developments in a parallel configuration interaction code for applications on complex systems Charles Cheung, Marianna Safronova, Mikhail G Kozlov, Sergey G Porsev We have continued the development of our new parallel atomic structure codes, improving the methods of constructing matrices. Our configuration interaction code now features a dynamic workload distribution method to form the Hamiltonian matrix, proving to be much more scalable than the previous static version. This allows for much more efficient use of many processors. The Davidson procedure has also been improved to allow a larger initial approximation to be considered in negligible time. We report the application of our codes to the calculation of the oscillatorstrength ratio of two Fe XVII transitions, which has recently been shown to finally agree with experiments (arXiv:2201.09070). 
Thursday, June 2, 2022 3:00PM  3:12PM 
U04.00006: Precision calculation of hyperfine constants for extracting nuclear moments of ^{229}Th. Sergey G Porsev, Marianna Safronova, Mikhail G Kozlov Determination of nuclear moments for many nuclei relies on the computation of hyperfine constants, with theoretical uncertainties directly affecting the resulting uncertainties of the nuclear moments. In this work, we improve the precision of such a method by including for the first time an iterative solution of equations for the core triple cluster amplitudes into the relativistic coupledcluster method, with largescale complete basis sets. We carried out calculations of the energies and magnetic dipole and electric quadrupole hyperfine structure constants for the lowlying states of ^{229}Th^{3+} in the framework of such relativistic coupledcluster single double triple (CCSDT) method. We present a detailed study of 
Thursday, June 2, 2022 3:12PM  3:24PM 
U04.00007: Fockspace relativistic coupledcluster calculation of the clock properties in twovalence Al^{+} ion. Ravi Kumar, Brajesh K Mani The recent advances in the development of new and improved frequency and time standards in optical domain provides a road map to study fundamental as well as technological applications. To mention some important applications, probing physics beyond the standard model of particle physics, searching for the variation in the fundamental constants, navigation systems, and the basis for the redefinition of the second [1  4]. The group13 ions are identified as the promising candidates for the accurate optical clocks as they are expected to have a low fractional frequency shift [5,6]. For example, the fractional frequency shift for ^{1}S_{0} – ^{3}P_{0} clock transition in Al^{+} is reported to be 9.4×10^{19 }[7]. Since the direct measurement of blackbody radiation shift is nontrivial, the accurate data from high precision atomic structure calculations are important in developing the new optical frequency standards. Considering the twovalence nature of Al^{+}, accurate calculation of the properties, however, requires the inclusion of electron correlation effects to the highest level of accuracy. 
Thursday, June 2, 2022 3:24PM  3:36PM 
U04.00008: Comprehensive calculations of energy levels, radiative transition parameters, hyperfine structure constants A_{J}  B_{J}, Landé g_{J} factors and isotope shifts for Sc XX Shikha Rathi, Lalita Sharma Atomic parameters are crucial for calculating stellar opacities, chemical abundance, developing sophisticated stellar atmosphere models, plasma diagnosis and modelling. Isotope shifts (IS) and hyperfine structures (HFS) are essential for precise and correct spectra analysis. Recently, studies on scandium have become an exquisite research topic as its energy levels, transition rates, weighted oscillator strengths, HFS are needed for the accurate study of nucleosynthesis processes, abundance anomalies in stars and plasma diagnosis. Sc is usually present in its ionic form in hightemperature plasma, and Helike ions have dominant features in Xray spectra of stars. Therefore we carry out large scale calculations of the energy levels, transition rates for multipole transitions, lifetimes, HFS constants, Landé g_{J} factors, and IS factors for the lowest 127 levels of Sc XX using the multiconfigurational Dirac–Fock procedure. GRASP2018 and RIS4 packages are used to perform the computation. The leading quantum electrodynamic corrections, Breit interaction, nuclear recoil effects and electron correlation effects on the atomic structures are also studied. An excellent agreement with the previously available results is observed. A large section of the results is reported for the first time. 
Thursday, June 2, 2022 3:36PM  3:48PM 
U04.00009: Relativistic perturbationtheory calculations for actinide atoms and ions Igor M Savukov, James Colgan Actinide atoms and ions present challenges to atomic theory calculations due to a large number of electrons and their complicated interactions. Conventional approaches such as calculations based on Cowan’s code are limited and require a large number of parameters for energy agreement. One promising approach is relativistic configurationinteraction and manybody perturbation theory (CIMBPT) methods. We will present CIMBPT results for various uranium and plutonium atoms and ions. Among atomic properties, energies, gfactors, electric dipole moments, lifetimes, hyperfine structure constants, and isotopic shifts will be discussed. While some progress is made, more work is needed for better understanding these challenging atomic systems. 
Thursday, June 2, 2022 3:48PM  4:00PM 
U04.00010: A Science Gateway for Atomic, Molecular and Optical Science(AMOS): Democratizing AMOS Research and Education Barry I Schneider, Klaus R Bartschat, Kathryn R Hamilton, Lincoln D Carr, Igor Bray, Armin Scrinzi, Fernando Martin, Jesus G Vasquez, Andrew Brown, Jimena D Gorfinkiel, Sudhakar Pamidighantam, Robert R Lucchese, Nicolas Douguet, Charlotte F Fischer A group of internationally known atomic and molecular theorists are developing a computational portal (amosgateway.org) where practitioners can access a synergistic, fullscope platform for computational Atomic, Molecular, and Optical Science (AMOS). The AMOSGateway currently hosts eleven stateoftheart AMOS software suites and is powered by an advanced cyberinfrastructure (CI) enabling a flexible and easytouse platform for the broad AMOS community. The gatewayhosted AMOS applications are bestofbreed approaches for computing atomic spectra, transition probabilities, electron collision/photoionization processes, including the control of atomic and molecular systems by laseratom/molecule interactions. The AMOS scientific group is complemented by experts in CI and computational science capable of delivering advanced CI and highperformance computing integration expertise. The developers also deliver new capabilities to scientists interested in applications of AMOS data, and to researchers and educators who are not computational AMO scientists. The applications are directly accessed on the gateway, where they been compiled on a number of NSF compute systems. Users are able to access and modify input files for their own purposes and then submit them for execution on one of the NSF systems using the XSEDE AMOSGateway account. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2023 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700