We have applied a semiclassical impact-parameter close-coupling method to calculate the state-resolved excitation cross sections in proton collisions with the ground state of helium. Using both correlation-configuration and frozen-core two-electron basis functions, we construct a large number of helium pseudostates to use in the expansion of the total scattering wave function. Extensive convergence studies show that the present results are accurate to within a few percent. The present cross sections for transitions from the ground state into all $n\le 5$ states for the ${}^{1}S,{}^{1}P,{}^{1}D,{}^{1}F$, and ${}^{1}G$ symmetries agree very well with experimental data where available. This work serves to provide a comprehensive set of excitation cross sections that were previously available only in narrow energy regions and for some channels. Furthermore, we present elastic-scattering, total excitation, and total electron-loss cross sections from 2 to $2000\mathrm{keV}$. We conclude that with modern supercomputer technology, a single-center method can accurately model ${\mathrm{p}}^{+}+\mathrm{He}$ collisions through implicit inclusion of the electron-capture process via coupling to the large number of positive-energy pseudostates representing the continuum.

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• Electronic excitation & ionization
• Scattering of atoms, molecules, clusters & ions
• Atoms
• Ions
• Configuration interaction
• Nonperturbative methods
• Semiclassical methods