The First principle calculation of bulk modulus and Young's modulus for amorphous carbon material

Abstract

The dependence of bulk modulus and Young's modulus on mass density for hydrogen-free amorphous carbon structures were investigated by using the first principle calculation on density functional theory. The amorphous carbon structures with various mass densities were generated by the numerical operations of structure relaxation from the random structures and volume relaxation. The bulk modulus and Young's modulus increased in proportion to the mass density. We uses the number densities of sp2 and sp3 atoms in place of these fractions or ratios as a classification parameter of amorphous carbon material because the number density of sp3 atoms can fit the both of amorphous carbon and diamond by one straight line in bulk modulus and Young's modulus. By this analysis, we suggest that the increases of the bulk modulus and Young's modulus are derived from only the sp3 carbon atom. © Published under licence by IOP Publishing Ltd.