摘要
利用群论和对称性分析的方法探讨了具有Td对称性构型的C24+分子的声子态对称性、电声耦合及其对称性破缺与能级分裂等相关问题.首先研究了C24+分子的声子态对称性及其活跃声子态,发现C24+分子存在3种不同的声子态a1,e,t2,其中只有e,t2是活跃声子态;随后探讨了系统声子间的耦合情况,结果表明,e-e与e-t2等声子间的耦合均能产生耦合声子态.最后研究了3种不同类型的杨-泰勒系统的对称性破缺方向与能级分裂,发现T■e系统的对称性破缺方向是Td→D2d,畸变后C24+分子的基态是D2d群下的A2;T■t2系统的对称性破缺方向是Td→C3v,畸变导致C24+分子的基态能级T1分裂为C3v群下的A2与E,其中A2是畸变后的系统基态;T■(e+t2)系统的对称性破缺方向是Td→C2v,畸变导致系统的基态能级T1分裂为3条,它们分别具有C2v群下的A2,B1与B2对称性,其中B2态是畸变后C24+分子的基态.
The symmetry of phonon states,vibronic coupling,symmetry breaking and energy level splitting for C2+4 molecules with Td symmetry are discussed using group theory and the methods of symmetry analyses.First of all,the symmetry of phonon states for C2+4 molecules are studied in this paper,it is found that C2+4 molecules have three phonon states with a1,e and t2 symmetry under the group Td,the active phonon states of C2+4 molecules are e and t2.Afterwards,the phonon coupling of C2+4 molecules are discussed,it is found that the e phonon coupling produces a1 and e coupling phonon states.Finally,three types systems of vibronic coupling are studied in the paper,the symmetry breaking direction of the T■e system is Td→D2d,the ground state of the system after the distortion is A2 under the group D2d.The symmetry breaking direction of the T■t2 system is Td→C3v,the original ground state of the system is separated into A2 and E under the group C3v because of vibronic coupling,the ground state of the system after the distortion is A2.The symmetry breaking direction of the T■(e+t2) system is Td→C2v,the original ground state T1 of the system is separated into A2,B1 and B2 under the group C2v because of vibronic coupling,and the state B2 is the ground state of the system after the distortion.
出处
《西北师范大学学报(自然科学版)》
CAS
北大核心
2013年第1期36-40,71,共6页
Journal of Northwest Normal University(Natural Science)
基金
广东省自然科学基金资助项目(34613)
关键词
对称性
声子态
电声耦合
对称性破缺
能级分裂
symmetry
phonon state
vibronic coupling
symmetry breaking
energy level splitting