​​​Svetlana Kotochigova​ Group

  

We combined a number of the most accurately measured transition frequencies in hydrogen and deuterium, recent quantum electrodynamics calculations (QED), and a generalized least-squared analysis to obtain precise predictions for hydrogen and deuterium energy levels and transition frequencies with principle quantum numbers upto 200 and all allowed orbital and total angular momenta. The interest in such highly-accurate data lies in the development of frequency standards and for tests of QED. 

   

Our theoretical analysis is based on current knowledge of the revelant contributions from relativistic, quantum electrodynamic, recoil, and nuclear size effects. Quoted uncertainties take into account uncertainties in the theoretical calculations, uncertainties in the fundamental constants, and covariances between the various contributions. Our results are presented in two publications: Can. J. Phys. 80, 1373-1382 (2002) and PRL 95, 163003 (2005) and in the interactive database at

http://www.nist.gov/pml/data/hdel/index.cfm. 

   

We applied the relativistic multiconfiguration Dirac-Fock method to X-ray spectroscopy of highly-charged ions. This project is intended to establish "benchmark" atomic data to be used for plasma diagnostics and for X-ray astrophysics. Our computational approach has unique features designed for an efficient description of correlation effects. It includes the use of Dirac-Fock and Sturm functions as the basis set and second-order perturbation theory to account for highly excited states. Based on this method we performed highly-accurate calculations of transition wavelengths and oscillator strenghts for Fe XVIII upto Fe XX. This work was presented at the International conference on X-ray Diagnostics of Astrophysical Plasma, November 2004 and published in two papers (XDAP Conference Proceedings 774, 161 (2005), PRA 76, 052513 (2007) and Astrophysical Journal Supplement Series 186, 85 (2010)).