Speaker
Tapio Ala-Nissilä
(Dept. of Applied Physics, Aalto SCI, Espoo, Finland)
Description
Over the last few years novel two-dimensional materials and
nanoscopically thin heteroepitaxial overlayers have
attracted intense attention due to their unusual properties
and important technological applications. Many physical
properties of these systems such as thermal conductivity and
electrical transport are intimately coupled to the large
scale mechanical and structural properties of the materials.
However, modeling such properties is a formidable challenge
due to a wide span of length and time scales involved. In
this talk, I will review recent significant progress in
structural multi-scale modeling of two dimensional materials
and thin heteroepitaxial overlayers [1], and graphene in
particular [2], based to a large extent on the Phase Field
Crystal (PFC) model combined with standard microscopic
modeling methods (classical Molecular Dynamics and quantum
density functional theory). The PFC framework allows one to
reach diffusive time scales for structural relaxation of the
materials at the atomic scale, which facilitates
quantitative characterisation of domain walls, dislocations,
grain boundaries, and strain-driven self-organisation up to
almost micron length scales. This allows one to study e.g.
thermal conduction and electrical transport in realistic
multi-grain systems [3].
References
1. K. R. Elder et al,. Phys. Rev. Lett. vol. 108, 226102
(2012); Phys. Rev. B vol. 88, 075423 (2013); J. Chem. Phys.
144, 174703 (2016).
2. P. Hirvonen et al., Phys. Rev. B 94, 035414 (2016).
3. Z. Fan et al., to be published.
