Calculation of the correlation energy of molecules by many-body rayleigh-schrödinger perturbation theory up to third order

1977 ◽  
Vol 51 (1) ◽  
pp. 170-174 ◽  
Author(s):  
M. Urban ◽  
V. Kellö ◽  
I. Hubač
Keyword(s):  
Perturbation Theory ◽  
Correlation Energy ◽  
Many Body ◽  
Third Order ◽  
Schrödinger Perturbation

Correlation energy in triplet electronic states. Application of the many-body Rayleigh-Schrödinger perturbation theory in the restricted Roothaan-Hartree-Fock formalism

1981 ◽  
Vol 46 (6) ◽  
pp. 1324-1331 ◽  
Author(s):  
Petr Čársky ◽  
Ivan Hubač
Keyword(s):  
Wave Function ◽  
Perturbation Theory ◽  
Correlation Energy ◽  
Electronic States ◽  
Many Body ◽  
Third Order ◽  
Explicit Formulas ◽  
Hartree Fock ◽  
The Many ◽  
Schrödinger Perturbation

Explicit formulas over orbitals are given for the correlation energy in triplet electronic states of atoms and molecules. The formulas were obtained by means of the diagrammatic many-body Rayleigh-Schrodinger perturbation theory through third order assuming a single determinant restricted Roothaan-Hartree-Fock wave function. A numerical example is presented for the NH molecule.

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.

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