电荷转移型Hubbard模型的相图

The phase diagram of Hubbard model with alternating chemical potentials

用玻色化技术和高斯波泛函变分理论研究了电荷转移型Hubbard模型 .通过自旋密度波和电荷密度波的位相结构的变化 ,并结合其相应能隙的变化 ,得到以下结论 :系统的Ising相变与Mott相变不重合 ,中间有一个SDI(spontaneouslydimerizedinsulating)的过渡相 .在BI(band_insulator)相 ,自旋密度波与电荷密度波都具有能隙 ,而在MI(Mott_insulator)相 ,电荷密度波具有能隙 。

We have investigated the ground-state phase diagram of the one-dimensional Hubbard model with alternating chemical potentials at half-filling by bosonization technique and the Gaussian wave functional method. We calculate variations of the charge density wave (CDW) and the spin density wave (SDW) gaps, ad well as their classical trajectory phi(c,s) with increasing on-site Coulomb repoulsion potential. For the fixed potential, it is found that the transition from the band insulator ( BI) to the spontaneously dimerized insulator (SDI) is of the Ising type, at which charge gap vanishes, while the transition from SDI to the Mott insulator (Ml) is of the KT type.