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Quantum Stark broadening of Ar XV lines. Strong collision and quadrupolar potential contributions

We present in this paper electron impact broadening for six Ar XV lines using our quantum mechanical formalism and the semiclassical perturbation one. Additionally, our calculations of the corresponding atomic structure data (energy levels and oscillator strengths) and collision strengths are given as well. The lines considered here are divided into two sets: a first set of four lines involving the ground level: 1s$^{2}2$s$^{2}$ $^{1}$S$_{0}-$1s$^{2}2$s$n$p $^{1}$P$^{\rm o}_{1}$ where $2\leq n \leq5$ and a second set of two lines involving excited levels: 1s$^{2}2$s2p $^{1}$P$^{\rm o}_{1}-$1s$^{2}2$s3s $^{1}$S$_{0}$ and 1s$^{2}2$s2p $^{3}$P$^{\rm o}_{0}-$1s$^{2}2$s3s $^{3}$S$_{1}$. An extensive comparison between the quantum and the semiclassical results was performed in order to analyze the reason for differences between quantum and semiclassical results up to the factor of two. It has been shown that the difference between the two results may be due to the evaluation of strong collision contributions by the semiclassical formalism. Except few semiclassical results, the present results are the first to be published. After the recent discovery of the far UV lines of Ar VII in the spectra of very hot central stars of planetary nebulae and white dwarfs, the present -and may be further- results can be used also for the corresponding future spectral analysis.