Center for Functional Nanomaterials Colloquium

Connecting the underlying chemical processes with the growth and emergent form remains unsurmountable problem in life sciences [1]. In materials research, the current outlook is more optimistic: establishing such connection, from the basic interatomic forces to growing nanostructure shape and properties becomes a real possibility. We will discuss several important examples, focusing on two recent results. First one concerns the nanotubes, where it took two decades to derive a kinetic formula [2] R ~ sin x (growth rate R, helical angle x). Further analysis of the subtle balance between the kinetic and thermodynamic views reveals sharply peaked abundance distribution A ~ x exp (-x) [3]. This explains the puzzling (n, n-1) types observed in many experiments. In the second example, a combination of DFT and Monte Carlo models explains the low symmetry shapes of graphene on substrates. In equilibrium, edge energy variation dE manifests in slightly distorted hexagons. In growth, it enters as ~exp(-dE/kT), amplifying the symmetry breaking to triangle, ribbon, rhomb [4]. Third example concerns 2D materials of more complex chemistry, h-BN and MX2 among them, and how their defects, dislocations and grain boundaries, predicted from the first principles, find remarkable experimental confirmations [5]. [1] On Growth and Form, by D'Arcy W. Thompson (Cambridge U, 1917). [2] F. Ding et al. PNAS 106, 2506 (2009); R. Rao et al. Nature Mater. 11, 213 (2012). [3] V. Artyukhov - E. Penev et al. Nature Comm. 5, 489 (2014). [4] Y. Liu et al. PRL 105, 235502 (2010); V. Artyukhov et al. PNAS 109, 15136 (2012); Y. Hao et al. Science, 342, 720 (2013); V. Artyukhov et al. PRL 114, 115502 (2015). [5] X. Zou, et al. Nano Lett., 13, 253 (2013); S. Najmaei et al. Nature Materials, 12, 754 (2013); A. Aziz et al. Nature Comm., 5, 4867 (2014). *** Boris I. Yakobson is an expert in theory and computational modeling of materials na