Comment on "Pentadiamond: A Hard Carbon Allotrope of a Pentagonal Network of sp2 and sp3 atoms"

V. V. Brazhkin, M. V. Kondrin, A. G. Kvashnin +2

In a recent Letter [1] Y. Fujii et al. proposed a new carbon allotrope and claimed its extremely high Young's and shear moduli of 1691 and 1113 GPa, respectively, surpassing those…