The geometries of the low-lying isomers of phosphorus P2 to P10 were calculated using the semiempirical modified neglect of diatomic overlap method. It was found that, in those cases (P2 and P4) where spectroscopic data are available, the bond strengths are overestimated. The binding energies were found to be underestimated in those cases (P2, P3 and P4) where thermodynamically derived values for the gas phase are available. A roof-shaped tetramer is a prominent structural unit in low-lying states of P5, P6, P7 and P8; in the low-lying states of P6, P7, P8, P9 and P10, another prominent structural unit is some kind of roof-shaped pentamer. The geometrical shapes of P6 (C2v, with a P4 roof), P8 (O(h)) and P8 (C2v, wedge) show striking similarities to the corresponding valence-isoelectronic hydrocarbons benzvalene (CH)6, cubane (CH)8 and cuneane (CH)8 respectively.