Quantum chemical calculation of O-H vibration in LiOH. Ab-initio analysis of hydrogen isotopes in ceramic breeder materials

The stretching vibrational frequency of O-H in LiOH crystal was calculated using CRYSTAL98 code. Hartree-Fock (HF) and hybrid (B3LYP) methods were used. By taking account of reduced mass, O-D or O-T frequencies could be also estimated. The obtained O-D frequencies were 2,994 cm-1 in HF level and 2,740 cm-1 in B3LYP. Agreement with experimental data, 2,713 cm-1 reported by Buchanan et al., was much better in B3LYP than in HF. The result of the present calculation supported the assignment in our previous FT-IR study, where O-D vibration in the Li2O single crystal that was treated by thermal absorption of D2 was observed. The peak observed at 2,715 cm-1 was attributed to O-D in LiOD phase. The present study showed that the quantum chemical analysis combined with the FT-IR was a powerful tool to study the behavior of hydrogen isotopes in the ceramic breeder materials. (author)