LINEAR RESPONSE FUNCTION OF A MANY FERMION SYSTEM
Abstract
The properties of a many body system are studied by means of a linear response function which depends on frequency and wave number. It is shown how the expectation value of two body operators, the rate of transitions induced by one body operators or weak external fields acting on the system, and information about the energy spectrum can be found from this function. As a result, the formalism suggests many relationships between apparently dissimilar quantities, and suggests indirect ways of experimentally measuring internal properties of a system. In the present formalism, all of the difficulties inherent in many body calculations are related to the determination of the response function. However, there exist some rules and a priori conditions on this function which can be used to estimate the validity of approximate calculations and to indicate what must be done to improve the results. The response function is calculated for a Fermi gas by using a combined diagrammatic perturbation theory and Green's function technique. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1961
- Accession Number
- AD0262092
Entities
People
- Arnold J. Glick
Organizations
- Weizmann Institute of Science