Raman and IR spectra of butane: Anharmonic calculations and interpretation of room temperature spectra

► VSCF calculations closely reproduce IR and Raman experiments for butane. ► B3LYP is superior to MP2 for butane by the test of spectroscopy. ► Anharmonic effects in the CH band spectra are very large. ► Vibrational degeneracy effects in butane are washed out by broadening.