Plasma-screening effects are investigated on three-photon bound-bound transitions in hydrogen atoms embedded in weakly coupled plasmas. In the present context, we discuss a set of basis functions for the pseudostate method. The basis functions are obtained from the modified wave functions for screening Coulomb potential (Debye model) using the Ritz variation method. The calculated energy eigenvalues for various Debye lengths agree well with the other theoretical results. Our calculated transition amplitudes for free-atom case agree excellently with the existing results in the literature. We have calculated the three-photon transition matrix elements for various Debye lengths, showing the strong plasma effects on the three-photon bound-bound transition amplitudes for the plasmas-embedded hydrogen atom.

• Received 10 October 2008

DOI:https://doi.org/10.1103/PhysRevA.79.032714