ORIGINAL PAPER Search for structures, potential energy surfaces, and stabilities of planar B n P(n=1 ∼ 7) Rongwei Shi & Jingling Shao & Cheng Wang & Xiaolei Zhu & Xiaohua Lu Received: 6 January 2010 / Accepted: 6 July 2010 / Published online: 21 July 2010 # Springer-Verlag 2010 Abstract We have systematically explored and investigated the geometrical structures, stability, growth pattern, bonding character, and potential energy surface (PES) of the possible isomers of each cluster for planar B n P (n=1 ∼ 7) at the CCSD (T)/6-311+;G(d)//B3LYP/6-311+G(d) level. A large number of planar structures for the possible isomers of B n P (n=1 ∼ 7) and transition states are located. Isomers 1a ∼ 7a of B n P are the lowest-energy structures and 2a, 4a, as well as 6a are more stable than their neighbors. For the lowest-energy structures (1a ∼ 7a) of B n P, P atom lies at the apex and tends to form two B-P bonds with boron atoms. They exhibit planar zigzag growth feature or approximately spherical-like growth pattern. Results from molecular orbital analysis demonstrate that the formation of the delocalized π MOs and the σ-radial and σ-tangential MOs plays a critical role in stabilizing the structures of lowest-energy isomers (2a ∼ 7a) of B n P. Importantly, isomers 3a, 3c, 3d, 4a, 4b, 5b, and 5c of B n P are stable both thermodynamically and kinetically at the CCSD(T)/6-311+G(d)// B3LYP/6-311+G(d) level and de- tectable in laboratory, which is valuable for further experi- mental studies of B n P. Keywords Cluster . DFT . Isomerization . Potential energy surfaces (PES) . Stability Introduction The geometries, electronic structures, and stability of clusters, especially for mixed III–V group clusters, have received considerable attention in theoretical and experimental studies [1–17] in recent years. Boron clusters and doped boron clusters have attracted much interest both theoretically and experimentally [18–21], partly because of the desire of understanding how structures and physical properties evolve from atom to the bulk phase and partly because of the potential applications of cluster- based materials in different fields [22–48]. The equilibrium geometries and atomization energies for the ground states of B 2 ∼B 4 and B 6 have been reported at the MP4/6-31G(d) level by Whiteside [47]. Boustani investigated the geometry and electronic structures of B n (n ≤ 14) clusters based on quantum- chemical methods [35]. Yang et al. studied the geometries, potential energy curves, and spectroscopic dissociation ener- gies of ground and low-lying electronic states of B 2 and B 2 + using the ab initio quadratic CI calculation and 6-311G basis sets [49]. The neutral and anionic structures of B 3 and B 4 have been investigated using photoelectron spectroscopy and ab initio calculations by Zhai et al. [24]. The structure and stability of B n (n=5, 6, 7) have been systematically studied by Li and Ma based on the MP2 and density functional theory (DFT) methods, respectively [40, 41, 50]. B 8 clusters were investigated by Li and coworkers based on the MP2 and DFT methods [51]. Interestingly, experimental and computational studies revealed that small pure boron clusters tend to form planar or quasi-planar structures. It is well known that BP compound is refractory semiconductor and of considerable interest in solid state physics. The investigations on the geometrical growth feature and bonding nature in small clusters of technologically important material are interesting and challenging. So far, there have been some reports about P-doped boron clusters. Linguerri et al. carried out large scale ab initio calculations on Electronic supplementary material The online version of this article (doi:10.1007/s00894-010-0801-x) contains supplementary material, which is available to authorized users. R. Shi : J. Shao : C. Wang : X. Zhu (*) : X. Lu (*) State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China e-mail: xlzhu@njut.edu.cn e-mail: xhlu@njut.edu.cn J Mol Model (2011) 17:1007–1016 DOI 10.1007/s00894-010-0801-x