Differences in the properties of bulk materials from nano- and molecular materials is a well-appreciated observation. However, the exact length-scale at which the transitions take place is a matter of investigation. Extraordinary chemical, mechanical, optical, electrical and thermal properties of carbon nanostructures (fullerenes, graphenes, carbon nanotubes) have made them technologically important materials. An overwhelmingly large number of contributions towards their structure-property relationships have come from computational investigations and this contribution focuses on DFT investigations on C60 fullerene with particular attention to anisotropic strain energies resulting in improved mechanical strength of the molecule. A series of DFT-based computational investigations showed anisotropy in the strain energy of the molecule when sampled with respect to differences in the "pinning" of different combinations of opposite atoms of C60. The molecule was observed to be able to bear higher tensile energies before "rupture" when compared to compression energies. The strain energy in molecular materials varies as the square of the strain while it varies as the first power of the strain in bulk materials. However, in case of C60 fullerene, an interesting phenomenon, named Nonlinear-to-Linear Elastic Transition (NLET) was observed where a transition from molecular to bulk behaviour was observed at higher strains. While this phenomenon has been observed for the first time instigating the immediate need to deeper investigations to unravel the underlying science, this observation has also characterized C60 fullerene as a material with improved mechanical bearing when compared to other molecular materials not exhibiting the phenomenon of NLET. The study also impart light on possible length-scales at which molecular-to-bulk transition takes place with respect to mechanical properties of the materials.

Some computational experiments revealing anisotropic strain energies in C60 fullerene

2019 Spring National Meeting

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