Binding energies, vibrations and structural characteristics of small polyphosphorus molecules from quantum chemical computations

Abstract

A systematic search for a quick and cost-effective theoretical method suitable for simultaneous studies of the structures, spectra and atomization energies of polyphosphorus compounds has been performed. It is demonstrated that density functional theory in BPW91/cc-pVTZ formulation provides a reasonable description of small P_n (n = 2, 3, 4, 6) clusters and P_nR_m molecules (R = H, C(SiH₃)₃, n = 1, 2; m = 1, 2, 4), close to that achieved by far more expensive coupled cluster calculations. In order to assign intrinsic PP bond strengths compliance matrices have been calculated. It is shown that compliance constants of PP bonds provide a unique tool for assigning individual mechanical bond strengths in small cluster systems.