无自旋态反绝热极限下MX链晶体中的量子晶格涨落效应

EFFECT OF QUANTUM LATTICE FLUCTUATIONS ON MX CHAIN IN ANTI-ADIABATIC LIMIT AND SPINLESS CASE

MX链的准一维、电子跃迁、电子——声子耦合和电子——电子相互作用等物理特性决定着系统的相转变和对称破缺电荷密度波态的稳定性。从紧束缚Hamiltonian模型出发,在反绝热极限条件下,对费米子无自旋态MX链系统进行了研究。讨论了系统的电荷密度波态,二聚化相变、绝缘相能隙等。并根据基态能量的解析性质,得到确定导体相的Luttingcr指数。计算结果表明,在反绝热极限情况下,系统存在一非平凡相变点。电声子耦合强度大于临界值时,系统处于二聚化电荷密度波态,小于临界值时,系统处于Luttinger液体相。

The physical properties of quasi-one-dimension,electron supertransi-tion,electron-phonon coupling,and electron-electron interaction of MX chains determine the phase transition and stability of symmetry-broken charge-density-wave state of MX chain system. Based on the tight-binding Hamiltonian model,the anti-adiabatic limit of MX chain in spinless case is studied. The charge-density-wave state,dimeriza-tion transistion,and energy gap of insulator state are discussed. From the analysis of the property of ground state energy,the Luttinger index has been obtained. The result shows that in the case df anti-adiabatic limit,there exists dimerization transition point. When intensity of electron-phonon coupling is greater than the critical value ,the MX chain system is in the dimerization charge-density-wave state and when less the system is in the Luttinger liquid state.