Hartree-Fock plus correlation energy in the valence space

1988 ◽  
Vol 92 (4) ◽  
pp. 921-924 ◽  
Author(s):  
Renato Colle ◽  
Alessandro Fortunelli ◽  
Oriano Salvetti
Keyword(s):  
Correlation Energy ◽  
Valence Space ◽  
Hartree Fock

scholarly journals THE METHOD OF INCREMENTS — A WAVEFUNCTION-BASED AB-INITIO CORRELATION METHOD FOR SOLIDS

2007 ◽  
Vol 21 (13n14) ◽  
pp. 2204-2214 ◽  
Author(s):  
BEATE PAULUS
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Ground State ◽  
Infinite System ◽  
Correlation Energy ◽  
Correlation Method ◽  
Many Body ◽  
Hartree Fock ◽  
The Many ◽  
Good Agreement

The method of increments is a wavefunction-based ab initio correlation method for solids, which explicitly calculates the many-body wavefunction of the system. After a Hartree-Fock treatment of the infinite system the correlation energy of the solid is expanded in terms of localised orbitals or of a group of localised orbitals. The method of increments has been applied to a great variety of materials with a band gap, but in this paper the extension to metals is described. The application to solid mercury is presented, where we achieve very good agreement of the calculated ground-state properties with the experimental data.

VERTEX CORRECTIONS IN THE NUCLEAR SCHWINGER–DYSON FORMALISM

2002 ◽  
Vol 11 (04) ◽  
pp. 321-333 ◽  
Author(s):  
MASAHIRO NAKANO ◽  
HIROYUKI MATSUURA ◽  
TAISUKE NAGASAWA ◽  
KEN-ICHI MAKINO ◽  
NOBUO NODA ◽  
...  
Keyword(s):  
Field Theory ◽  
Correlation Energy ◽  
Mean Field Theory ◽  
Mean Field ◽  
The Other ◽  
Vertex Correction ◽  
Hartree Fock ◽  
Vertex Corrections ◽  
Negative Correlation Energy ◽  
Self Consistent

We develop the Nuclear Schwinger–Dyson (NSD) formalism to include the effects of ladder diagrams by modifying the vertex. In this extension, the NSD equation sums up both ring diagrams and ladder diagrams self-consistently. The results are compared with mean field theory, Hartree Fock and bare-vertex NSD calculations. It is shown that the vertex correction is important from the following viewpoints. First, the vertex correction greatly modifies the meson propagators, and we can avoid the ghost-pole from meson propagators in a self-consistent way. Secondly, it gives a large negative correlation-energy compared with the other calculations; as a result, it gives a softer equation of state which is preferable according to the experimental data.

Quadrupole polarizabilities and Sternheimer antishielding factors in the density functional theory

1982 ◽  
Vol 60 (2) ◽  
pp. 210-221 ◽  
Author(s):  
M. J. Stott ◽  
E. Zaremba ◽  
D. Zobin
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Closed Shell ◽  
Energy Functional ◽  
Functional Theory ◽  
Hartree Fock ◽  
Shielding Factor ◽  
The Density Functional Theory

The quadrupole polarizability and Sternheimer antishielding factor have been calculated for selected closed-shell atoms and ions using the density functional theory. In most cases, the results agree favourably with coupled Hartree–Fock calculations. However, for atoms with valence (d-shells the local density approximation used in the calculations is found to be inadequate. Our results suggest that refinements to the exchange-correlation energy functional are required in order to obtain accurate values for the polarizability and shielding factor of (d-shell atoms within a density functional approach.

Theoretical prediction of the singlet-triplet intercombination separations for NH, OH+, PH, and SH+

1968 ◽  
Vol 46 (17) ◽  
pp. 1989-1991 ◽  
Author(s):  
Paul E. Cade
Keyword(s):  
Theoretical Prediction ◽  
Correlation Energy ◽  
Quantitative Model ◽  
Hartree Fock ◽  
Relationship Of ◽  
The Relationship ◽  
Diatomic Hydride

The singlet–triplet (a1Δ–X3Σ−) intercombination separations for NH, OH +, PH, and SH + are predicted to be 1.63, 2.19, 0.95, and 1.16 eV, respectively. These predictions are expected to be good to ~0.1 eV and are based on a quantitative model of the relationship of the united atom and the diatomic hydride, AH. The intercombination separations as calculated via Hartree–Fock energies are corrected for the "change in correlation energy" involved in the transition making use of united-atom changes in the correlation energy.

Transition probability approach for direct calculation of coefficients of Configuration Interaction wave function

2017 ◽  
Author(s):  
Arijit Bag
Keyword(s):  
Wave Function ◽  
Configuration Interaction ◽  
Correlation Energy ◽  
Transition Probability ◽  
Direct Calculation ◽  
Energy Curve ◽  
Equilibrium Bond Length ◽  
Hydrogen Water ◽  
Hartree Fock ◽  
A New Technique

To reduce the computation cost of Configuration Interaction (CI) method, a new technique is used to calculate the coefficients of doubly excited determinants directly from orbital energies, orbital overlap matrix and electron population obtained from Hartree Fock level run. This approach to approximate the coefficients of CI wave function is termed as <b>transition probability approximated CI (TPA-CI).</b> In principle, calculated dynamical electron correlation energy of TPA-CI and Full CI (FCI) are equivalent. It is observed that computed TPA-CI correlation energies of hydrogen, water, ammonia and ozone are very close to FCI values, within 5% error. The potential energy curve of the hydrogen molecule is also studied and it is found that the energy is minimum at its equilibrium bond length.<br><br>

Sign in / Sign up

Export Citation Format

Share Document