Bond rotations at the Si(100) surface: Anharmonicity, chaotic dynamics, and signature of tilted-dimer reconstruction
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In our first-principles-based molecular dynamics simulations for Si(100), we have found that the total energy U(θ) is rather flat with respect to the bond-rotation angle θ for |θ|<10°, with shallow minima at the positions θ = ±θ0 corresponding to a tilted-dimer geometry. Here we calculate the Fourier transform of the atomic displacements, u(ω), and find a characteristic bond-rotation mode with ν to approximately 5 THz. This mode is primarily associated with the upper atom in a dimer, and appears to be a signature of the tilted-dimer reconstruction. At low temperature the vibrations are nearly harmonic, but at high temperature there is strong anharmonicity, and θ appears to exhibit chaotic behavior.
author list (cited authors)
Gryko, J., & Allen, R. E.