  An investigation of the mechanical, electronic, and optical properties of the
recently reported material K4 phosphorus was made in this work. The K4
phosphorus has been proved to be mechanically and dynamically stable up to 7
GPa under hydrostatic pressure. We compared the elastic anisotropy, average
acoustic velocity and Debye temperature of K4 phosphorus at 0 and 7 GPa. The
ideal tensile at large strains of K4 phosphorus was also examined, with the
results showing that it would cleave under the tensile strength of 8.5 GPa with
the strain of 0.3. In addition, the effect of tensile strain and pressure on
optical properties and band gap were studied.
