We calculate electronic excitation cross sections for the b${\mathrm{}}^3$${\mathrm{\Sigma }}_{\mathit{u}}^{+}$ a${\mathrm{}}^3$${\mathrm{\Sigma }}_{\mathit{g}}^{+}$ c${\mathrm{}}^3$${\mathrm{\Pi }}_{\mathit{u}}$, and d${\mathrm{}}^3$${\mathrm{\Pi }}_{\mathit{u}}$ states of ${\mathrm{H}}_2$ by electron impact. Our results were obtained with the Schwinger multichannel method with pseudopotentials and real potentials at the two-channel level of approximation. Pseudo-H atoms are used to generate ${\mathrm{H}}_2$ molecules with almost the same low-energy spectrum as the real molecules. We show that the dynamics of the electronic excitation process of the pseudomolecules by electron impact is very similar to the real case. Our results support the idea that pseudopotentials can be used to obtain reliable molecular electronic excitation cross sections by low-energy electron impact, confirming the expectations of previous studies with ${\mathrm{CH}}_2$O [Bettega et al., Phys. Rev. A 25, 1111 (1993)] and HBr [Rescigno, J. Chem. Phys. 104, 125 (1996)]. © 1996 The American Physical Society.

• Received 26 April 1996

DOI:https://doi.org/10.1103/PhysRevA.54.5435