Gutzwiller wavefunction is a physically well motivated trial wavefunction for describing correlated electron systems. In this work, a new approximation is introduced to facilitate evaluation of the expectation value of any operator within the Gutzwiller wavefunction formalism. The basic idea is to make use of a specially designed average over Gutzwiller wavefunction coefficients expanded in the many-body Fock space to approximate the ratio of expectation values between a Gutzwiller wavefunction and its underlying noninteracting wavefunction. To check with the standard Gutzwiller approximation (GA), we test its performance on single band systems and find quite interesting properties. On finite systems, we noticed that it gives superior performance than GA, while on infinite systems it asymptotically approaches GA. Analytic analysis together with numerical tests are provided to support this claimed asymptotic behavior. At the end, possible improvements on the approximation and its generalization towards multiband systems are illustrated and discussed.
Unifying Variational and Dynamical Quantum Embedding: From Ghost Gutzwiller Approximation to Dynamical Mean-Field Theory
Center for Computational Quantum Physics, Flatiron Institute（平顶山研究所计算量子物理中心）；Department of Physics, National Chung Cheng University（国立中正大学物理系）；Ames National Laboratory（艾姆斯国家实验室）；Department of Physics and Astronomy, Iowa State University（爱荷华州立大学物理与天文学系）；Physics and Astronomy Department, Rutgers University（罗格斯大学物理与天文学系）；Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory（布鲁克海文国家实验室凝聚态物理与材料科学系）；Physics Department, Boston University（波士顿大学物理系）；Université Paris-Saclay, CNRS, CEA, Institut de physique théorique（巴黎萨克雷大学、法国国家科学研究中心、法国原子能和替代能源委员会、理论物理研究所）；School of Physics and Astronomy, Rochester Institute of Technology（罗切斯特理工学院物理与天文学院）
Wavefunctions, electronic localization and bonding properties for correlated materials beyond the Kohn-Sham formalism
多体理论，如动力学平均场论（DMFT），使电子交换相关相互作用的描述是在当前的密度泛函理论（DFT）计算中丢失。然而，这些理论中的波函数相对较少。介绍了Elk-TRIQS接口的实现方法，以及如何用DMFT（DFT+DMFT）波函数计算DFT，该接口可用于计算DFT+DMFT波函数相关量。我们通过计算单层SrVO $_3$和CaFe $_2$ As $_2$中的电子局域函数（ELF）来说明这一点，这提供了一种可视化它们的化学键的方法。单层SrVO $_3$ ELF对DFT、单次DFT+DMFT和完全电荷自洽DFT+DMFT计算之间的电荷重新分布敏感。在四重态和坍缩的四重态CaFe $_2$ As $_2$中，电子能级随As-p和Fe-d杂化态的电荷重分布的变化很小.尽管如此，层间的As-As键在崩溃的四元结构是强大的费米能级和周围的变化。
