New allotropic forms of carbon based on С$_{60}$ and С$_{20}$ fullerenes with specific mechanical characteristics

New allotropic forms of carbon based on С$_{60}$ and С$_{20}$ fullerenes are considered. The most stable carbon compounds are found using an evolution algorithm, and their crystal structure (X-ray diffraction spectra) and electron (band structure) and mechanical (moduli of elasticity, hardness) characteristics are studied. The carbon phase with the tetragonal symmetry with mechanical properties close to those of a diamond crystal and having a narrow band gap is found.