Theoretical modelling of surface phonons

Abstract

Abstract:We present a mini review of progress made towards theoretical modelling of surface phonons. We outline the essential ingredients of two theoretical methods, viz. an adiabatic bond charge method for semiconductor surfaces and the ab-initio density-functional perturbation method for solid surfaces in general. From the results of theoretical calculations we establish trends and criteria for the existence of localized phonon modes on group-IV(001) and III-V(110) semiconductor surfaces. We further obtain signatures of characteristic vibrational modes which develop during dissociative molecular adsorption on Si(001) surfaces. The results are compared with available experimental measurements. Some remarks are forwarded regarding manipulation of surface phonon modes for scientific advances and technological applications.

Assessment, improvement, and comparison of different computational tools used for the simulation of heat transport in nanostructures

“…The thermal transport simulation is performed by using a MD approach describing atomic interactions with different levels of approximation and, therefore, with different computational performance in the treatment of systems with a large number of atoms in the nanometric scale. 3,4 We consider for the atomic interactions the two following models: (a) a classical Tersoff potential; and (b) an adapted TB potential for MD simulations.…”

“…However, in the case of empirical approximations mainly, the price to pay is less transferability for systems with a large surface-to-volume ratio, requiring a critical analysis when it is applied to small systems. 3,4 In this work, we study the thermal transport of silicon nanosystems, modeling the atomic interactions using: (1) a classic empirical potential of Tersoff-Brenner (Tersoff) 5,6 over two closed software packages 7,8 ; and (2) a semiempirical tight-binding (TB) potential 9,10 over an in-house software. To do that we recreate a non-equilibrium thermodynamical state by means of Langevin's MD simulation for both potential models.…”

“…However, in the case of empirical approximations mainly, the price to pay is less transferability for systems with a large surface-to-volume ratio, requiring a critical analysis when it is applied to small systems. 3,4…”

Thermal conductance of structured silicon nanocrystals

“…vibrational modes of the lattice. Structural factors, stresses, nanopatterings, deformations, lattice discontinuities, among others, can affect the thermal transport [2,5,[7][8][9][10]. Nanostructured low dimensional systems usually have a very large surface-to-volume ratio that can enhance the surface effects on the thermal transport due to phonon scattering mechanisms.…”