講演者：Sung G. Chung 氏（Western Michigan University）
日時：５月　１８日（金）　午後４時３０分から
場所： 青山学院大学　理工学部（相模原キャンパス）Ｌ棟６階　Ｌ６０３室

題目： 「Entanglement perturbation theory: idea, recent 
developments and prospect for quantum chemistry」


要旨：
　Numerical renormalization group, DMRG being the champion, 
has been an important player in theoretical understanding 
of strong correlation phenomena in condensed matter and 
related fields. Over the last decade in particular, we have 
seen some explosive developments along the lines of DMRG, 
highlighting the concept of matrix, tensor product representations 
of state vectors and operators, with a great hope that we are 
close to a satisfactory description of many-body physics in 
two space dimensions, only to find nature’s stubborn resistance 
to an accurate numerical analysis. The difficulty may be of two 
kinds, numerical stability and computational accuracy. On one hand, 
numerical-RG is well known for its numerical stability with, 
however, apparent lack of accuracy in two space dimensions. 
On the other hand, if one pursues computational accuracy in 
non-RG methods, numerical instability caused by a dangerous 
nonlinearity is a serious issue. In this talk, I will introduce 
EPT as a non-RG many-body method, demonstrate its competitiveness 
in comparison with DMRG, and discuss its prospect for quantum 
chemistry, which bares essentially the same issue as in two 
space dimensions.
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