A density functional study on the structures and energies of CnP4- (n=1∼7) clusters

Using molecular graphics software, numerous models of CnP4- (n = 1 similar to 7) have been designed. Geometry optimization and calculation on vibrational frequency were carried out by means of the B3LYP density functional method. After comparing the total energies of the isomers, it was found that the ground state structures of CP4- and C2P4- are planar ring ones. The most stable structures of CnP4- (n = 3, 5, 7) are straight carbon chains connected a P3C ring at one end and a phosphorus atom at the other. The ground state structures of CnP4- (n = 4, 6) are not planar with straight carbon chains with a P-3 ring connected at one end and a phosphorus atom at the other. Other than a number of individual isomers, the structures with carbon and phosphorus atoms connected alternately are less and unstable. Most of the stable models are with C-2, C-3 and C-4 units in the form of ring or chain connected to different phosphorus units.