# Random-Phase-Approximation

The random phase approximation (english random- phase approximation, RPA, dt about, Proximity random phase ') is an approximate method for treating quantum mechanical many-body systems, the generalized Hartree -Fock approximation, or more generally, the molecular field theory and sometimes as dynamic Hartree - Fock approximation is called. The method is used for example in nuclear physics for the description of collective excitations.

RPA is a microscopic method to describe the structure of collective excitation from one particle 1-hole conditions, which corresponds to a simple approximation diagramatischen ( summing up the so-called bubble- diagrams).

The method is related to the Tamm - Dancoff approximation ( TDA), but differs in that ground state correlations are possible.

Special cases are the quasiparticle random- phase approximation ( QRPA ), relativistic random- phase approximation ( RRPA ), continuum quasiparticle random- phase approximation ( CQRPA ), relativistic quasiparticle random- phase approximation ( RQRPA ).

- Quantum mechanics