Multi‐Configurational Reference Perturbation Theory with a CASSCF Reference Function

2020 ◽  
pp. 299-353
Author(s):  
Roland Lindh ◽  
Ignacio Fdez. Galván
Keyword(s):  
Perturbation Theory ◽  
Reference Function

Multiplicity of many-body wavefunctions using unrestricted Hartree-Fock reference functions

1988 ◽  
Vol 53 (10) ◽  
pp. 2203-2213 ◽  
Author(s):  
George D. Purvis ◽  
Hideo Sekino ◽  
Rodney J. Bartlett
Keyword(s):  
Perturbation Theory ◽  
Coupled Cluster ◽  
Spin Projection ◽  
Many Body ◽  
Spin Multiplicity ◽  
Reference Function ◽  
Hartree Fock ◽  
Many Body Perturbation Theory ◽  
Reference Functions

Spin multiplicity formulae for the correlated Many Body Perturbation Theory (MBPT) and Coupled Cluster (CC) methods based upon an unrestricted Hartree Fock (UHF) reference function are presented and applied to evaluate the multiplicity in calculations of first row atoms. Spin projection in CC theory is discussed.

Second-order perturbation theory with a CASSCF reference function

1990 ◽  
Vol 94 (14) ◽  
pp. 5483-5488 ◽  
Author(s):  
Kerstin. Andersson ◽  
Per Aake. Malmqvist ◽  
Bjoern O. Roos ◽  
Andrzej J. Sadlej ◽  
Krzysztof. Wolinski
Keyword(s):  
Perturbation Theory ◽  
Second Order ◽  
Order Perturbation ◽  
Order Perturbation Theory ◽  
Reference Function ◽  
Second Order Perturbation Theory

A Perturbation Theory for the Population of Atomic Energy Levels in Non-Lte Plasmas

1988 ◽  
Vol 102 ◽  
pp. 343-347
Author(s):  
M. Klapisch
Keyword(s):  
Perturbation Theory ◽  
Small Parameter ◽  
Classification Scheme ◽  
Sum Rules ◽  
Energy Levels ◽  
Natural Classification ◽  
Quantum Numbers ◽  
Formal Expansion ◽  
Atomic Energy Levels ◽  
As Effects

AbstractA formal expansion of the CRM in powers of a small parameter is presented. The terms of the expansion are products of matrices. Inverses are interpreted as effects of cascades.It will be shown that this allows for the separation of the different contributions to the populations, thus providing a natural classification scheme for processes involving atoms in plasmas. Sum rules can be formulated, allowing the population of the levels, in some simple cases, to be related in a transparent way to the quantum numbers.

Sign in / Sign up

Export Citation Format

Share Document