Green’s function theory

Diagrammatic Green s function theory attempts to evaluate a perturbation expansion for... 

The accurate description of the electronic structure of atoms and molecules is a fundamentally difficult problem, and it is not surprising that there are no quick and dirty means of obtaining accurate answers. In our discussion we have attempted to relate these many-body methods to the traditional wave function techniques of bound-state quantum mechanics. We have indicated some similarities between these approaches, and at the same time have demonstrated how the EOM-Green s function theories have features not found in the conventional methods, leading to new and useful insights. 

The EOM-Green s function theories differ fundamentally from conventional methods in that they are based op a Liouville operator formalism, whereas the wave function theories deal with the Hamiltonian operator. We have discussed in detail what constitutes a complete basis set for these many-body methods and have proved that they do not suffer from the problem encountered by more naive Liouville operator formalisms. 

A recent report on the PE spectrum of 137 has been questioned on the basis of calculations using Green s function theory. A comparison of the experimental spectrum with the results of a calculation for 137 and 138 clearly favors 138. 

Analysis of Green s functions can be useful in seeking to establish model hamil-tonians with the property of giving approximately correct propagators, when put in the equations of motion. In this section, we explore a particularly simple model in order to familiarize the reader with various molecular orbital concepts using the terminology of Green s function theory. We employ the Hartree-Fock approximation and seek the molecular Fock operator matrix elements... 

We have seen that in single-particle quantum mechanics the Green s function has poles at values of equal to the eigenvalues of the Hamiltonian. To generalize Green s function theory to many-particle systems, we first consider an independent particle description, such as the Hartree-Fock (HF),... 

Here we investigate the conductivity of the artificial DNAs and compare the results with those of the natural DNAs by means of he scattering Green s function theory. In the following we briefly summarize the theory and apply it to the model DNA systems. 

We summarized theoretical description for I-V curve of molecular junction proposed by Luo et al. Based on the scattering Green s function theory, matrix element T is expressed by a function of energy Ei (energy at which scattering process is observed) as following. 

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