Data for: Structural, Electronic and Mechanical Properties of all-sp$^2$ Carbon Allotropes with Density Lower Than Graphene

Data report the x (second colum), y (third column), z (fourth column) cartesian coordinates of the atomic centers whose atomic species are specified in the first column (C = carbon). First line of the file reports the number of atoms in the unit cell, second line the cell size defining the periodic boundary conditions. Data are all in Angstrom.