Ab initio study of the Jahn-Teller distortion in the B_4~+

摘要

An ab initio study of the Jahn-Teller distortion of the B_4~+ molecule is performed using quadratic configuration interaction with all single and double substitutions (QCISD) and 6-311G~* basis set. For this cation, the D_(2h) rectangle and rhombus), D_(4h), C_(2v) (planar and non-planar), D_(∞h) structures are fully optimized and analyzed using energies, bond lengths and angles, harmonic frequencies and group theory. The results obtained predict a new minimum energy structure of B_4~+ cluster, i.e. C_(2v) configuration (non-planar) for the first time. At the same time, it is observed that the rectangle and square structures are not minima but saddle points. It is observed that Jahn-Teller distortion occurs in both B_4~+ (T_d) and B_4~+ (D_(4h)) geometries, and the symmetries of the distortions are in agreement with the predictions of group theory. The most stable geometry of B_4~+ is D_(2h) (rhombus). Based on this, the dissociation energies are computed and compared with the other theoretical and experimental work.