Relativistic Photoionization Computations with the Time Dependent Dirac Equation

Abstract

Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Ionization of inner shell electrons by laser fields often occurs in the relativistic regime. A complete description of this phenomenon requires both relativistic and quantum mechanical treatment. The Dirac equation describes the motion of a spin one-half particle in an external electromagnetic field. The stationary states in both Coulomb and soft-core potentials are solved either analytically or numerically. These are used as initial conditions in time dependent calculations. It is found that, at least in one case, two-dimensional simulations predict a greater ionization rate than the one predicted by the Coulomb corrected strong field approximation. Computational performance is important due to the rapid oscillations in a relativistic wavefunction. Multiple General Purpose Graphical Processing Units are utilized in parallel to speed up calculations. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S)