Higher order (A+E) ⊗ e pseudo-Jahn-Teller coupling

Abstract

The pseudo-Jahn-Teller (PJT) coupling of a nondegenerate state A with a twofold degenerate state E by a degenerate vibrational mode e is studied for a general system with a C3 main rotational axis. The PJT coupling terms up to sixth order are derived by symmetry considerations for this general (A+E) ⊗e case. The obtained expression for the 3×3 diabatic potential energy matrix is found to be closely related to the expression recently developed for the higher order Jahn-Teller case [A. Viel and W. Eisfeld, J. Chem. Phys. 120, 4603 (2004)]. The dynamical PJT coupling, which can arise for states of appropriate symmetry if one of the vibrational modes induces a change of the nuclear point group between D3h, C3v, C3h, and C3, is discussed. The effect of the higher order PJT coupling is tested by a two-dimensional model study based on the e bending mode of N H3+. The models are analyzed by fitting the two-dimensional potential energy surfaces. The significance of the higher order terms on the nonadiabatic dynamics is demonstrated by quantum wave packet propagations. © 2005 American Institute of Physics.