Raman spectra of nitrogen-doped tetrahedral amorphous carbon from first principles

The non-resonant vibrational Raman spectra of nitrogen-doped tetrahedral amorphous carbon have been calculated from first principles, including the generation of a structural model, and the calculation of vibrational frequencies, vibrational eigenmodes and Raman coupling tensors. The calculated Raman spectra are in good agreement with the experimental results. The broad band at around 500 cm^-1 arises from mixed bonds. The T peak originates from the vibrations of sp³ carbon and the G peak comes from the stretching vibrations of sp²-type bonding of C=C and C=N. The simulation results indicate the direct contribution of N vibrations to Raman spectra.