Shibuya, TaiIchi and McKoy, Vincent (1970) Higher RandomPhase Approximation as an Approximation to the Equations of Motion. Physical Review A, 2 (6). pp. 22082218. ISSN 05562791. http://resolver.caltech.edu/CaltechAUTHORS:SHIpra70

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Abstract
Starting from the equations of motion expressed as groundstate expectation values, we have derived a higherorder randomphase approximation (RPA) for excitation frequencies of lowlying states. The matrix elements in the expectation value are obtained up to terms linear in the groundstate correlation coefficients. We represent the ground state as eUHF〉, where U is a linear combination of two particlehole operators, and HF〉 is the HartreeFock ground state. We then retain terms only up to those linear in the correlation coefficients in the equation determining the ground state. This equation and that for the excitation energy are then solved selfconsistently. We do not make the quasiboson approximation in this procedure, and explicitly discuss the overcounting characteristics of this approximation. The resulting equations have the same form as those of the RPA, but this higher RPA removes many deficiencies of the RPA.
Item Type:  Article 

Additional Information:  ©1970 The American Physical Society Received 10 June 1970 Arthur Amos Noyes Laboratory of Chemical Physics Contribution No. 4071. 
Record Number:  CaltechAUTHORS:SHIpra70 
Persistent URL:  http://resolver.caltech.edu/CaltechAUTHORS:SHIpra70 
Alternative URL:  http://dx.doi.org/10.1103/PhysRevA.2.2208 
Usage Policy:  No commercial reproduction, distribution, display or performance rights in this work are provided. 
ID Code:  6317 
Collection:  CaltechAUTHORS 
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Deposited On:  01 Dec 2006 
Last Modified:  26 Dec 2012 09:20 
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