  Phonon dispersions in <100> silicon nanowires (SiNW) are modeled using a
Modified Valence Force Field (MVFF) method based on atomistic force constants.
The model replicates the bulk Si phonon dispersion very well. In SiNWs, apart
from four acoustic like branches, a lot of flat branches appear indicating
strong phonon confinement in these nanowires and strongly affecting their
lattice properties. The sound velocity (Vsnd) and the lattice thermal
conductance (kl) decrease as the wire cross-section size is reduced whereas the
specific heat (Cv) increases due to increased phonon confinement and
surface-to-volume ratio (SVR).
