A5055018967- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Cold Atom Physics and Bose-Einstein Condensates
- Nuclear physics research studies
- Oil Spill Detection and Mitigation
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-induced spectroscopy and plasma
- Oceanographic and Atmospheric Processes
- High-pressure geophysics and materials
- Electron and X-Ray Spectroscopy Techniques
- Atmospheric and Environmental Gas Dynamics
- Atomic and Subatomic Physics Research
- Quantum Chromodynamics and Particle Interactions
- Mass Spectrometry Techniques and Applications
- Quantum and Classical Electrodynamics
- Advanced Frequency and Time Standards
- Laser-Plasma Interactions and Diagnostics
- Advanced Physical and Chemical Molecular Interactions
- Particle physics theoretical and experimental studies
- Marine and coastal ecosystems
- Laser-Matter Interactions and Applications
- Particle accelerators and beam dynamics
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Arctic and Antarctic ice dynamics
University of Notre Dame
2008-2024
United States Department of the Interior
1991-2021
University of Nevada, Reno
2004-2017
Ocean Energy (Norway)
2017
Bureau of Energy
2017
History of Science Society
2012-2013
Information Management Services
1999-2012
Lawrence Livermore National Laboratory
1995-2012
NSF National Center for Atmospheric Research
2007
Princeton University
2007
The Breit interaction is reviewed with applications to heavy atoms in mind. Generalizations of the which avoid expansion powers electron velocities are discussed. Two-particle matrix elements and its generalizations given a form convenient for numerical applications. Expressions derived evaluating configuration-averaged atomic energy shifts generalizations. Numerical results ground states presented selected range $Z=2$ $Z=102$; interpolated values graphically all considered. A breakdown...
The van der Waals coefficients for the alkali-metal atoms from Na to Fr interacting in their ground states are calculated using relativistic ab initio methods. accuracy of calculations is estimated by also evaluating atomic static electric-dipole polarizabilities and interaction with a perfectly conducting wall. results excellent agreement latest data studies magnetic field induced Feshbach resonances ultracold collisions Rb atoms. For Cs we provide critically needed collision studies.
A multichannel relativistic random-pjase approximation (RRPA) for the photoionization of atoms is presented. The RRPA equations are obtained by generalizing nonrelativistic time-dependent Hartree-Fock using Dirac-Breit Hamiltonian to describe atomic electrons. angular decomposition a set coupled radial wave functions given, and radiative-transition operators developed arbitrary electric magnetic multipoles. Formulas total cross sections distributions, including all method constructing...
Energies of n=2 states for ions the lithium isoelectronic sequence are calculated from Z=3--92, starting a Hartree-Fock potential and including second- third-order correlation corrections, lowest-order Breit interaction with retardation treated exactly, second-order corrections to interaction, reduced mass polarization. The resulting differences between theory experiment 2p fine structure 2s-2p splittings found be in rough agreement one-electron Lamb shift, but clear deviations can seen. A...
A many-body calculation of the parity-nonconserving amplitude for 6${\mathit{s}}_{1/2}$\ensuremath{\rightarrow}7${\mathit{s}}_{1/2}$ transition in atomic cesium with an error order 1% is presented, ${\mathit{E}}_{\mathrm{PNC}}$=-0.906[9] (${\mathit{Q}}_{\mathit{W}}$/-N)i\ensuremath{\Vert}e\ensuremath{\Vert}${\mathit{a}}_{0}$\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$. Using this result to determine ${\mathit{Q}}_{\mathit{W}}$ from high-precision measurements leads a...
An all-order procedure is used to determine the energies of n=1 and n=2 states heliumlike ions with nuclear charges in range Z=3--100. The Coulomb wave functions are obtained from a no-pair Hamiltonian by an iterative scheme that sums all orders many-body perturbation theory. Breit energy determined taking expectation value instantaneous between functions. Corrections for frequency dependence interaction two interactions included. Quantum-electrodynamic mass-polarization corrections taken...
A novel technique employing $B$ splines is introduced that permits the precise evaluation of multiple sums over excited states occurring in higher-order many-body perturbation theory. As a test technique, accurately known nonrelativistic expression for second-order energy helium $\frac{1}{Z}$ approximation first calculated. The corresponding relativistic then evaluated entire isoelectronic sequence with attention to proper treatment negative-energy states.
Multichannel photoionization calculations using the relativistic random-phase approximation for outer shells in rare gases, neon, argon, krypton, and xenon, are presented. Total cross sections partial $\mathrm{ns}$ subshells determined compared with experiment alternative at low energies. Branching ratios of $^{2}P_{\frac{3}{2}}:^{2}P_{\frac{1}{2}}$ which sensitive to correlation effects presented experiment. Angular distribution asymmetry parameters $\ensuremath{\beta}$ each subshell found...
All-order methods recently developed for high-accuracy calculation of energies and matrix elements in Li are extended applied to cesium. We employ a relativistic, linearized, coupled-cluster formalism, incorporating single, double, an important subset triple excitations. A formulation the element one-body operator, random-phase approximation exactly, is used calculate hyperfine constants transition-matrix elements. find agreement with experiment at 0.5% level or better ionization...
High-precision measurements of atomic parity-nonconserving transitions in cesium when coupled with calculations similar accuracy allow for a precise determination ${Q}_{W}$, the weak nuclear charge. When expressed terms $Z$ mass, radiative corrections to ${Q}_{W}$ are insensitive top-quark so such allows particularly sensitive probe depending on new physics. While wave function cesium, atom which most accurate have been made, is extremely complex, theory has advanced point where predictions...
Valence removal energies, hyperfine constants, and E1 transition amplitudes are calculated for the 2${s}_{1/2}$, 2${p}_{1/2}$, 2${p}_{3/2}$, 3${s}_{1/2}$ states of Li ${\mathrm{Be}}^{+}$. This calculation is an extension earlier second- third-order many-body perturbation theory (MBPT) calculations, in which now infinite subset MBPT terms evaluated using all-order methods. Agreement with experiment at 0.01% level 0.1% matrix elements, found. Issues involved those higher-order omitted by...
The self-energy of $K$ electrons in atoms with atomic numbers the range $70\ensuremath{\le}Z\ensuremath{\le}90$ is determined numerically. Detailed theoretical evaluations $K$-electron binding energies including all effects $O(\ensuremath{\alpha}m{c}^{2})$ are given for four heavy closed-subshell - W, Hg, Pb, and Rn considered. With present values electron self-energy, $K$-shell these elements found to agree experimental determinations better than 1 part ${10}^{4}$.
Eigenfunctions and eigenvalues of the relativistic no-pair Hamiltonian are determined for n=2 triplet states heliumlike ions with charges in range Z=5--100. The eigenfunctions expanded a basis two-electron wave functions constructed from Dirac-Coulomb orbitals restricted to finite cavity. matrix is evaluated Davidson's method then used determine lowest few eigenvalues. These calculations, which include Coulomb interaction retarded Breit interaction, corrected QED mass-polarization effects...
The relativistic random phase approximation RRPA is developed from linearized time-dependent Hartree-Fock theory. Applications of the resulting many-body equations to determine excitation energies and oscillator strengths along He, Be, Mg, Zn Ne isoelectronic sequences are discussed compared with other recent experimental theoretical work. multi-channel treatment photoionization described applications given total cross sections, branching ratios, angular distributions autoionizing resonances.
The recently introduced technique of constructing finite basis sets from B-splines for use in atomic-physics calculations is applied to the alkali-metal atoms Li, Na, K, Rb, and Cs. Valence energies are calculated within framework many-body perturbation theory second order, corrections hyperfine splitting transition matrix elements third order approximation that a dominant subset terms this associated with Brueckner orbitals, evaluated. Agreement experiment at 1% level found all considered....
Relativity in atomic and molecular physics.- Foundations.- Relativistic wave equations for free particles.- The Dirac Equation.- Quantum electrodynamics.- Computational structure.- Analysis approximation of Hamiltonians.- Complex atoms.- Computation structures.- properties.- Continuum processes many-electron Molecular structure methods.- calculation Frequently used formulae data.- Supplementary mathematics.- mathematics.
The Beutler-Fano autoionizing resonances in the rare-gas atoms argon, krypton, and xenon are studied using relativistic multichannel quantum-defect theory (MQDT). Dynamical parameters for MQDT analyses obtained from an ab initio relativistic-random-phase-approximation calculation. position profile of these good agreement with experimental measurements. Angular distribution spin polarization photoelectrons resonance regions also close recent
We develop a theoretical method within the framework of relativistic many-body theory to accurately treat correlation corrections in atoms with few valence electrons. This combines all-order approach currently used precision calculations properties monovalent configuration-interaction that is applicable for many-electron systems. The applied Mg, Ca, Sr, Zn, Cd, Ba, and Hg evaluate ionization energies low-lying energy levels.
Third-order many-body perturbation theory is used to obtainE1 transition amplitudes for ions of the lithium and sodium isoelectronic sequences neutral alkali-metal atoms potassium, rubidium, cesium, francium. Complete angular reductions first-, second-, third-order are given. Tables energies rates given 2p1/2→ 2s1/2, 2p3/2→ 3s1/2→ 2p1/2, 2p3/2transitions in sequence corresponding 3p1/2→ 3s1/2, 3p3/2→ 4s1/2→ 3p1/2, 3p3/2transitions sequence. For alkali atoms, ofnp1/2→ ns1/2,np3/2→ ns1/2, (n+...
Energies of the ten (2l2${\mathit{l}}^{\ensuremath{'}}$) states ions beryllium isoelectronic sequence are determined to second order in relativistic many-body perturbation theory. Both second-order Coulomb interaction and Breit-Coulomb included. Corrections for frequency-dependent Breit taken into account lowest only. The effect Lamb shift is also estimated Comparison with experiment other theoretical data made. \textcopyright{} 1996 American Physical Society.
Theoretical expressions for the electric and magnetic susceptibilities shielding factors of closed-shell atoms ions are derived from point view relativistic random-phase approximation. These evaluated to determine electric-dipole, electric-quadrupole, magnetic-dipole susceptibilities, noble-gas isoelectronic sequences, as well selected having closed $s$, $d$, $f$ shells. Comparisons given with previous theoretical work experiment.