论文标题
数值重新归一化组的动力光谱函数：一种完整的激发方法
Dynamical Spectral Function From Numerical Renormalization Group: A Full Excitation Approach
论文作者
论文摘要
对于给定的量子杂质模型，Wilson的数值重归其化组（NRG）自然定义了NRG Hamiltonian，其确切的特征性和征收征可以可以获得。我们给出了NRG Hamiltonian的自由能，静态和动力学数量的精确表达式。该方法的动态光谱函数包含完整的激发，包括内部和壳间激发。对于Spin-Boson模型，我们比较了从当前方法获得的光谱函数和全密度矩阵（FDM）方法，表明两者都保证了严格的总和规则，但完整的激发方法避免了FDM方法的因果关系问题。
For a given quantum impurity model, Wilson's numerical renormalization group (NRG) naturally defines a NRG Hamiltonian whose exact eigenstates and eigenenergies are obtainable. We give exact expressions for the free energy, static, as well as dynamical quantities of the NRG Hamiltonian. The dynamical spectral function from this approach contains full excitations including intra- and inter-shell excitations. For the spin-boson model, we compare the spectral function obtained from the present method and the full density matrix (FDM) method, showing that while both guarantee rigorous sum rule, the full excitation approach avoids the causality problem of FDM method.
