A tight-binding molecular dynamics study of vibrational spectra of H-covered diamond (100) surfaces

Vibrational spectra of the hydrogen-terminated diamond (100) surfaces were investigated using the tight-binding molecular dynamics method. For the C(100)-(2 x 1):H surface the calculations allowed us to identify the symmetric and antisymmetric stretching C-H vibrations at 2916 and 2934 cm(-1), respectively, the former being more intense in the infrared spectrum than the latter. The simulations performed at a higher temperature reveal a strong anharmonic coupling of the C-H vibrations. The C-C-H bending vibrations are found to be coupled to the lattice modes and to spread over a wide spectral interval. The vibrational spectrum of the dihydride C(100):2H surface shows wide bands, again due to strong anharmonic motion of atoms in a stressed surface structure. Although the calculated infrared spectrum is in a qualitative agreement with the HREELS spectrum of Lee and Apai (S.T. Lee and G. Apai, Phys. Rev. B 48 (1993) 2684), further computational studies are necessary to verify the results. (C) 2000 Elsevier Science B.V. All rights reserved.