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Ground state of the impurity Anderson model revisited: A projector operator solution
Author(s) -
RouraBas P.,
Hamad I. J.,
Anda E. V.
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201451520
Subject(s) - anderson impurity model , hamiltonian (control theory) , physics , ground state , projector , bethe ansatz , ansatz , spins , quantum mechanics , kondo effect , renormalization , quantum electrodynamics , magnetization , impurity , condensed matter physics , magnetic field , mathematics , quantum , mathematical optimization , optics
By means of a projector operator formalism we study the ground state properties of the Anderson Impurity Hamiltonian. The non‐perturbative treatment of the model agrees with the previous one, obtained by Inagaki [Prog. Theor. Phys. 62 , 1441 (1979)] by means of a perturbation expansion with respect the hybridization term. We go beyond the Inagaki's formalism to the next leading order. It provides a very accurate calculation of the energy spectrum in the total spin S T = 0 sector and, in particular, the ground state energy in the whole parameter space. For a one body spinless system, the dependence of the ground state energy as a function of the impurity level obtained by this procedure remarkably agrees with analytical results. For the many body case the occupancy of the impurity as a function of the parameters is studied and it agrees with the corresponding one obtained by using the Bethe ansatz and the Numerical Renormalization Group solution of the Hamiltonian. The magnetization and susceptibility of the impurity is analyzed by studying the response of the system to an external magnetic field, from which it is possible to extract the Kondo temperature. The dependence of the Kondo scale with the parameters of the model is in excellent agreement with well‐known results.