M. T. Yin

Quantum mechanical force calculations in solids: The phonon spectrum of Si

Abstract Quantum mechanical force calculations with a realistic charge distribution for Si are reported here. Using the momentum-space expression for the Hellman-Feynman theorem, forces on displaced Si atoms corresponding to Γ, L, and X phonon modes are calculated. This frozen phonon model, based on the Born-Oppenheimer approximation, gives results within 5% of the experimental phonon frequencies. Anharmonic effects are briefly discussed using the calculated force constants.

Self-consistent electronic structure for a Mo (001) surface with saturated H adsorption

Abstract The band structure for a Mo (001) surface covered with a saturated monolayer of hydrogen is calculated self-consistently using the pseudopotential method in a mixed-basis representation. Two adsorbate bands are found below the bottom of the molybdenum bulk bands. Most of the intrinsic surface states of the clean (001) surface also exist on the hydrogen covered surface at lower energies. The results are used to identify H induced structures observed in recent photoemission studies of hydrogen on W (001).