Interaction between PH3 and small water clusters: Understanding the electronic and spectroscopic properties

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In this study, an investigation was performed to understand the interaction between phosphine and (H2O)n clusters (n=1–6). The general interactions involving PH3 and H2O molecules include P⋯HO and P⋯OH with bond distances of 2.412–3.065 and 3.174–3.471Å, respectively. A redshift of the vibrational modes corresponding to the phosphine-degenerated deformation and the symmetric deformation was observed. In addition, a blueshift of the vibrational modes corresponding to symmetric and asymmetric P–H stretching was predicted. A decrease in the dipole moments for the P–H bond contribution was also predicted. In addition, an increase in the phosphorous atom polarizability as well as a slight decrease in the phosphorous p population and an increase in the s population of the P–H bond were estimated. Based on analysis of the atomic charge distribution, the atomic charge distributions were dependent on the population analysis employed, and only some methods were able to characterize the correct behavior of these systems, while most of the population analysis failed to determine the phosphorous charge. The relative stability of the isomers and their dissociation energies were also predicted using Coupled Cluster and Møller–Plesset correlation energy correction. The efficiency of different Density Functional Theory (DFT) methods was evaluated using three basis sets [i.e., 6-311++G(2df, 2pd), 6-311++G(3df, 3pd) and aug-cc-pVTZ]. In these analyses, several functionals, including the generalized gradient approximation (GGA), hybrid-GGA, meta-hybrid-GGA, meta-GGA, double-hybrid-GGA, and functionals such as the empirical London dispersion correction were employed. Most of the functionals exhibited good performance, however the O3LYP, B97-2 and BHandH functionals exhibited the poorest performances.