中国物理B ›› 2006, Vol. 15 ›› Issue (5): 1015-1021.doi: 10.1088/1009-1963/15/5/025
施德恒1, 刘玉芳2, 孙金锋3, 朱遵略3, 杨向东4
Shi De-Heng (施德恒)abc, Liu Yu-Fang (刘玉芳)b, Sun Jin-Feng (孙金锋)bc, Yang Xiang-Dong (杨向东)c, Zhu Zun-Lue (朱遵略)bc
摘要: The reasonable dissociation limit of the A1∑+ state $^{7}$LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space for the first time. The whole potential energy curve and the dipole moment function for theA1∑+ state are calculated over a wide internuclear separation range from about 0.1 to 1.4\,nm. The calculated equilibrium geometry and dissociation energy of this potential energy curve are of R_{\e}=0.2487\,nm and D_{\e}=1.064\,eV, respectively. The unusual negative values of the anharmonicity constant and the vibration-rotational coupling constant are of \textit{\omega }_{\e}\textit{\chi }_{\e}=--4.7158cm^{ - 1} and \textit{\alpha }_{\e}=--0.08649cm^{ -1}, respectively. The vertical excitation energy from the ground to the A1∑+ state is calculated and the value is of 3.613\,eV at 0.15875nm (the equilibrium position of the ground state). The highly anomalous shape of this potential energy curve, which is exceptionally flat over a wide radial range around the equilibrium position, is discussed in detail. The harmonic frequency value of 502.47cm1 about this state is approximately estimated. Careful comparison of the theoretical determinations with those obtained by previous theories about the A1∑+ state dissociation energy clearly shows that the present calculations are much closer to the experiments than previous theories, thus represents an improvement.
中图分类号: (Bond strengths, dissociation energies)