扩展系统中的Drude和超流重量：不连续性和$δ$ -峰在一体和二体动量密度中的作用
Drude and Superfluid Weights in Extended Systems: the Role of Discontinuities and $δ$-peaks in the One and Two-Body Momentum Densities
摘要：
导电性的问题被重新讨论。利用总动量位移算符构造微扰多体哈密顿量和基态波函数，将基态能量对微扰场的二阶导数表示为一体和二体动量密度。绝热和包络函数导数之间的区别，因此德鲁德和超流重量之间的区别可以直接引入。结果表明，动量密度的不连续性对Drude重量有贡献，但对超流重量无贡献，而对两体动量密度的$δ$函数（如BCS波函数）对两个量均有贡献.动量密度的不连续性和本地化之间的连接也被证明。
英文摘要：
The question of conductivity is revisited. Using the total momentum shift operator to construct the perturbed many-body Hamiltonian and ground state wave function the second derivative of the ground state energy with respect to the perturbing field is expressed in terms of the one and two-body momentum densities. The distinction between the adiabatic and envelope function derivatives, hence that between the Drude and superfluid weights can be introduced in a straightforward manner. It is shown that a discontinuity in the momentum density leads to a contribution to the Drude weight, but not the superfluid weight, however a $δ$-function contribution in the two-body momentum density (such as in the BCS wave-funtion) contributes to both quantities. The connection between the discontinuity in the momentum density and localization is also demonstrated.
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