On the computation of electronic correlation energies within the local approach

A recently developed local approach to the computation of electron‐correlation energies is extended and investigated in great detail. For that purpose it is applied to the Ne atom and the CH4 molecule for which correlation‐energy calculations are available. It is shown that the local approach exhausts up to a few percent the correlation energy which is obtainable within a given basis set. A detailed comparison with conventional CI methods reveals the advantages of the present approach. Only a fraction of the two‐electron matrix elements Vijkl has to be calculated, and the number of required configurations is drastically reduced. Furthermore, CH4 is used as an example to demonstrate that the correlation‐energy calculations for large systems can be broken up into ones for small systems.

[1]  L. Cooper,et al.  Theory of superconductivity , 1957 .

[2]  M. Gell-Mann,et al.  Correlation Energy of an Electron Gas at High Density , 1957 .

[3]  J. Linnett,et al.  A Modification of the Lewis-Langmuir Octet Rule , 1961 .

[4]  O. Sǐnanoğlu,et al.  MANY-ELECTRON THEORY OF ATOMS AND MOLECULES. I. SHELLS, ELECTRON PAIRS VS MANY-ELECTRON CORRELATIONS , 1962 .

[5]  J. Hubbard.  Electron correlations in narrow energy bands , 1963, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[6]  Wilfried Meyer,et al.  PNO–CI Studies of electron correlation effects. I. Configuration expansion by means of nonorthogonal orbitals, and application to the ground state and ionized states of methane , 1973 .

[7]  H. Lischka,et al.  PNO–CI (pair natural orbital configuration interaction) and CEPA–PNO (coupled electron pair approximation with pair natural orbitals) calculations of molecular systems. II. The molecules BeH2, BH, BH3, CH4, CH−3, NH3 (planar and pyramidal), H2O, OH+3, HF and the Ne atom , 1975 .

[8]  B. Lundqvist,et al.  Exchange and correlation in atoms, molecules, and solids by the spin-density-functional formalism , 1976 .

[9]  Wilfried Meyer,et al.  Theory of self‐consistent electron pairs. An iterative method for correlated many‐electron wavefunctions , 1976 .

[10]  P. Fulde,et al.  A local approach to the computation of correlation energies of molecules , 1977 .

[11]  P. Fulde,et al.  Description of intraatomic correlations by the Local Approach , 1978 .

[12]  R. Ahlrichs,et al.  Computation of the complexation energies of BH3NH3 and BH3PH3 , 1978 .

[13]  P. Botschwina.  A PNO-CI and CEPA investigation of unstable boron-nitrogen and boron-oxygen compounds , 1978 .

[14]  S. Peyerimhoff,et al.  Potential curves for dissociative electron attachment of CFCl3 , 1979 .

[15]  P. Horsch,et al.  On the theory of electronic correlations in solids , 1979 .