CAJ | 학술논문

利用群论和对称性分析的方法研究了具有D3d对称性构型的B2H6分子的声子态及其声子间耦合等问题。研究发现,B2H6存在5种不同的声子态,它们分别具有D3d群下的a1g、a1u、a2u、eg与eu对称性,其中a2u与eu具有红外活性,a1g和eg具有拉曼活性,而a1u是非活性的;在B2H6的声子态中只有eg是活跃的声子态;活跃声子态eg与eg之间的耦合作用将会产生耦合声子态a1g和eg;B2H6分子的电声耦合作用一定会导致B2H6分子发生杨-泰勒畸变,畸变致使B2H6分子从D3d对称性降低到C2h对称性。
이용군론화대칭성분석적방법연구료구유D3d대칭성구형적B2H6분자적성자태급기성자간우합등문제。연구발현,B2H6존재5충불동적성자태,타문분별구유D3d군하적a1g、a1u、a2u、eg여eu대칭성,기중a2u여eu구유홍외활성,a1g화eg구유랍만활성,이a1u시비활성적;재B2H6적성자태중지유eg시활약적성자태;활약성자태eg여eg지간적우합작용장회산생우합성자태a1g화eg;B2H6분자적전성우합작용일정회도치B2H6분자발생양-태륵기변,기변치사B2H6분자종D3d대칭성강저도C2h대칭성。
The symmetries of phonon states and phonon couplings for B2 H6 molecules with D3a symmetry configuration are analyzed by using group theory and the methods of symmetry analyses in this paper. First of all, the symmetries of phonon states for B2H6 molecules are studied, and the infrared and Raman activities of the vibration modes of the molecule are discussed. Then, the vibronic coupling and the active phonon states for B2H6 molecules are analyzed. Finally, the phonon couplings for B2H6 molecules are further studied also by using group theory, and the CG coefficient of the phonon coupling is computed by using Mathematica program. The results show： B2H6 molecules have five kinds of phonon states, they have the symmetries of als ,alu ,a2u,eg and eu under the group D3d. The phonon states a2 and e, refer to infrared activity, the phonon states a1g and eg refer to Raman activity, the phonon state alu is inactive. Among the phonon states of B2H6 molecules, only the phonon state eg is the active phonon state. The coupling between the phonon eg and eg should generate the coupling phonons a1g and eg. The symmetry of B2H6 molecules should be lowered to C2h from D3d because of the vibronic coupling of B2H6 molecules.