[Hou, Xi-Wen] Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China
; [Chen, Jing-Hua] Huazhong Normal Univ, Dept Informat Management, Wuhan 430079, Peoples R China
; [Wan, Ming-Fang] Wuhan Univ Technol, Sch Nat Sci, Wuhan 430079, Peoples R China
; [Ma, Zhong-Qi] Inst High Energy Phys, Beijing 100049, Peoples R China
Quantum entanglement of anharmonic stretches in molecules H2O and SO2 is studied in terms of the reduced-density linear entropy with initial squeezed vacuum states and thermal states. It is shown that the entropy of both kinds of initial states with a small amplitude (n) over bar is quasi-periodic with the period of thermal states being larger than that of squeezed vacuum states for each molecule. The entropy evolution of both kinds of initial states with a larger amplitude (n) over bar is irregular. For each kind of initial state, the frequency of oscillation of the entropy for SO2 is larger than that for H2O. That can be useful in quantum computing based on vibrational states in H2O and SO2.