Electron-impact excitation of Ne4+

We present the results of extensive close-coupling calculations of electron-impact excitation of the C-like ion, Ne4+. We first compare effective collision strengths determined from a 20-level Breit-Pauli R-matrix calculation with those obtained from a 20-level intermediate-coupling frame transformation (ICFT) R-matrix calculation. The ICFT method was also employed to perform two much larger calculations; we compare the effective collision strengths determined from these calculations with each other and with those obtained from the 20-level calculations in order to assess the effects of increasing both the size of the configuration-interaction expansion of the target and the size of the close-coupling expansion. Our final calculation, with 130 terms and 261 levels in the configuration-interaction expansion of the target and 66 terms and 138 levels in the close-coupling expansion, provides improved data for excitation between the levels of the 2s(2)2p(2), 2S2p(3) and 2p(4) configurations and the first close-coupling results for excitation to the levels of the 2s(2)2p3l configurations in Ne4+.