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(1 00)-(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), respe ctively, the former being more intense in the infrared spectrum than the la tter. The simulations performed at a higher temperature reveal a strong anh armonic coupling of the C-H vibrations. The C-C-H bending vibrations are fo und to be coupled to the lattice modes and to spread over a wide spectral i nterval. The vibrational spectrum of the dihydride C(100):2H surface shows wide bands, again due to strong anharmonic motion of atoms in a stressed su rface structure. Although the calculated infrared spectrum is in a qualitat ive agreement with the HREELS spectrum of Lee and Apai (S.T. Lee and G. Apa i, Phys. Rev. B 48 (1993) 2684), further computational studies are necessar y to verify the results. (C) 2000 Elsevier Science B.V. All rights reserved .