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|Date and time:||27th April (Tue.) 16:00〜|
|Place:||Lecture room 739, 7F, Faculty of Science, University of Hyogo|
|Title:||Ground state and some excited states of asymmetric spin ladder and spin tube|
|講演者:||五十嵐亮 氏 （原子力機構・システム計算科学センター）|
|Speaker:||Dr. Ryo Igarashi (JAEA)|
Spin ladder and Spin tube system have attracted much attention since these systems are the intermediates between 1D and 2D quantum systems. We calculated the low energy spectrum of the asymmetric S=1/2 spin tube and spin chain system using our directly-extended two-dimensional density-matrix renormalization-group (dex-DMRG) method. We focus on 3-leg spin tube system up to L=256 where the inter-chain coupling(J2) is weaker than the inner-tube one(J1). We computed the lowest 10 eigenvalues on the S=0 and S=1 sectors and determined the degeneracy structure. Moreover, we calculated the fully periodic lattice with extension to our dex-DMRG code. We found that the excited state structure changes around J2/J1=0.5, which may indicate the possible gap-less region. We will also discuss the comparison between the 5-leg spin tube and the 5-leg spin ladder system.