The formulation given by Smith et al., for transitions induced by electron impact among ground-state terms of atoms or ions with configurations 2p$ or 3pQ, is corrected. Closecoupling equations are solved numerically for electrons incident on C, N, O, N + , 0 + , and 0 ++ . Shape resonances are found in low-energy elastic scattering by ground-state carbon and nitrogen atoms. Peaks in electron-atom inelastic cross sections are found to occur at lower energies than those calculated by Smith et al., and the magnitude of the cross sections is lower at high energies. Collision strengths for electron scattering by 0 + , N + , and 0 ++ are presented.

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Calculations have been made on the elastic scattering of low-energy electrons by helium using a variational procedure which takes polarization and correlation effects into account by means of continuum Bethe-Goldstone equations. The convergence of the results is examined using two methods to obtain a complete set of basis functions. Results for the s, p, d, and f waves are presented. The width of the 28 closed-channel resonance below the n =2 threshold is found to be 0.015 eV, in comparison with the 0.015-0.020-eV estimates of Andrick and Ehrhardt from experiment and the 0.01-eV estimate of simpson and Pano.