R-matrix calculations of the integral electron-impact excitation cross sections of the ground state of the barium atom

The R-matrix approach has been used to calculate the integral cross sections of excitation of the barium atom by low-energy electrons. The collision strengths have been calculated in the 38-state close coupling approximation, including 16 physical states and 22 pseudostates of the target. The target wave functions have been obtained in terms of the multiconfiguration Hartree-Fock method in the LS coupling scheme. The cross sections calculated exhibit a pronounced resonance structure, which contributes significantly to the total excitation cross sections. The results obtained have been compared to available theoretical and experimental data.