Premium
The coupled perturbed electron propagator in the two‐particle‐hole and extended two‐particle‐hole Tamm‐Dancoff approximations
Author(s) -
Deleuze Michael S.,
Pickup Barry T.
Publication year - 1997
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1997)63:2<483::aid-qua19>3.0.co;2-9
Subject(s) - propagator , physics , quadratic equation , third order , electron , quantum mechanics , electronic correlation , quantum electrodynamics , statistical physics , mathematics , geometry , philosophy , theology
The equations satisfied by the first‐order perturbed electron propagator in an applied external field are examined at a level equivalent to the two‐particle‐hole Tamm‐Dancoff and extended two‐particle‐hole Tamm‐Dancoff approximations (2ph‐TDA). These schemes are derived with the intention of evaluating linear and quadratic response properties through second and third order in correlation. Their derivation is based on a combination of the diagrammatic and algebraic superoperator methods. Both schemes account for the polarization of the 2p‐1h and 2h‐1p responses and bielectron interactions under an external field. The 2ph‐TDA scheme is correct up to second order in electronic correlation and includes infinite geometric series of mixed RPA‐ladder‐type character. Its extended version is derived consistently through third order and accounts for a first‐order screening of the external field and bielectron interaction by the effects of electronic correlation. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 483–509, 1997