Distorted-wave-approximation cross sections for excitation of the $b{}_{}{}^3{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$ and $B{}_{}{}^1{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$ states of ${\mathrm{H}}_2$ by low-energy-electron impact

Distorted-wave-approximation calculations are reported for the excitation of the $b{}_{}{}^3{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$ and $B{}_{}{}^1{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$ states of ${\mathrm{H}}_2$ by electron impact. A discrete-basis-set method is used to obtain the electron-molecule continuum wave functions. Differential and integrated cross sections are presented from near threshold up to 60-eV electron impact energy. Comparison is made with other theoretical results and experimental data.