The cations and anions of P-5, P-7 and P-9 exhibit intensities of significance on the mass spectra of phosphorus clusters produced in direct laser vaporization. We have acquired in the total fifty isomers of P-5, P-7, P-9 and their cations and anions by means of the B3LYP, DFT method. According to total energies, the most stable isomers have been predicted. A cationic cluster prefers to adopt structures with an atom(s) which is four-fold coordinated. The planar pentagon structure is a frequent sub-unit in the phosphorus clusters. Both tetrahedral P-4 and cuneane P-8 are common components of the clusters and can be considered as important units for the construction of large clusters.