  A recent breakthrough has been achieved by synthesizing monolayer amorphous
carbon (MAC), which introduces a material with unique optoelectronic
properties. Here, we used ab initio (DFT) molecular dynamics simulations to
study silicon and germanium MAC analogs. Typical unit cells contain more than
600 atoms. We also considered their corresponding nanotube structures. The
cohesion energy values for MASi and MAGe range from -8.41 to -7.49 eV/atom and
follow the energy ordering of silicene and germanene. Their electronic behavior
varies from metallic to small band gap semiconductors. Since silicene,
germanene, and MAC have already been experimentally realized, the corresponding
MAC-like versions we propose are within our present synthetic capabilities.
