chaotic dynamics, and signature of tilted-dimer reconstruction Bond rotations at the Si(100) surface: Anharmonicity

In our first-principles-based molecular dynamics simulations for Si(100), we have found that the total energy U() is rather flat with respect to the bond-rotation angle for ||<10, with shallow minima at the positions = 0 corresponding to a tilted-dimer geometry. Here we calculate the Fourier transform of the atomic displacements, u(), and find a characteristic bond-rotation mode with 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 appears to exhibit chaotic behavior.

Bond rotations at the Si(100) surface: Anharmonicity, chaotic dynamics, and signature of tilted-dimer reconstruction Conference Paper