Excited states and photochemistry of saturated molecules. Minimal plus Rydberg basis set calculations on the vertical spectra of CH4, C2H6, C3H8, and n-C4H10

Basis sets consisting of STO4G plus a set of one s and three p Rydberg functions are developed for methane, ethane, propane, and n-butane. These basis sets are then used to predict the vertical electronic spectra for the same four molecules using a limited CI. The results are found to be in reasonable agreement with experiment and with more sophisticated calculations on ethane and propane.