Brillouin-Wigner Perturbation Theory as a Possible more Effective Alternative to Many-Body Rayleigh-Schrodinger Perturbation Theory and Coupled Cluster Theory

1995 ◽  
Vol 60 (9) ◽  
pp. 1419-1428 ◽  
Author(s):  
Petr Čársky ◽  
Vojtěch Hrouda ◽  
Vladimír Sychrovský ◽  
Ivan Hubač ◽  
Peter Babinec ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Computational Methods ◽  
Effective Alternative ◽  
Coupled Cluster ◽  
View Point ◽  
Many Body ◽  
Coupled Cluster Theory ◽  
Cluster Theory ◽  
Schrödinger Perturbation

Brillouin-Wigner perturbation theory is revisited using the Lippmann-Schwinger equation and applied to the H2O molecule. The results obtained are examined from the view-point of the development of practical computational methods.

RANDOM PHASE APPROXIMATION FOR ALLOWED AND PARITY NON-CONSERVING ELECTRIC DIPOLE TRANSITION AMPLITUDES AND ITS CONNECTION WITH MANY-BODY PERTURBATION THEORY AND COUPLED-CLUSTER THEORY

2006 ◽  
Vol 05 (04) ◽  
pp. 945-956
Author(s):  
GEETHA GOPAKUMAR ◽  
CHIRANJIB SUR ◽  
BHANU PRATAP DAS ◽  
RAJAT K. CHAUDHURI ◽  
DEBASHIS MUKHERJEE ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Electric Dipole ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Coupled Cluster ◽  
Phase Approximation ◽  
Many Body ◽  
Coupled Cluster Theory ◽  
Cluster Theory ◽  
Many Body Perturbation Theory

The connections between the Random Phase Approximation (RPA) and Many-Body Perturbation Theory (MBPT) and its all order generalization, the Coupled-Cluster Theory (CCT), have been explored. Explicit expressions have been derived for the electric dipole amplitudes for allowed and forbidden transitions induced by the parity non-conserving neutral weak interaction. The Goldstone diagrams associated with the RPA terms in both cases are shown to arise in MBPT and CCT, and the numerical verification of this relationship is made for the allowed electric dipole transitions.

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