Finding the structure of phosphorus in the phase IV

We have explored the unknown structure of the phosphorus in the phase IV (P-IV phase) based on the first-principles calculations using the metadynamics simulation method. Starting from the simple cubic structure, we found a new modulated structure of a monoclinic lattice. The modulation is crucial to the stability of the structure. Refining further the structure by changing the modulation period, we have found the structure which shows the X-ray powder pattern in the best agreement with the experimental one.We can not exclude the possibility that the unknown structure of the phase IV of phosphorus is an incommensurately modulated one.