%0 Journal Article %1 hollett:114111 %A Hollett, Joshua W. %A Gill, Peter M. W. %D 2011 %I AIP %J The Journal of Chemical Physics %K chemistry correlation electron fock hartree quantum static theory %N 11 %P 114111 %R 10.1063/1.3570574 %T The two faces of static correlation %U http://link.aip.org/link/?JCP/134/114111/1 %V 134 %X Restricted Hartree–Fock (RHF) and UHF wavefunctions for beryllium-like ions with nuclear charge 3 ⩽ Z ⩽ 5 are found using a near-complete Slater basis set. The triplet (RHF → UHF) instability and correlation energy are investigated as a function of Z and we find that the instability vanishes for Z > 4.5. We reproduce this surprising behavior using a minimal-basis model and, by comparing with the stretched H2 molecule, conclude that “static” (also known as nondynamical, near-degeneracy, first-order, or strong) correlation comes in two flavors: one that can be captured by UHF and another that cannot. In the former (Type A), there is an “absolute near-degeneracy”; in the latter (Type B), there is a “relative near-degeneracy.” This dichotomy clarifies discussions of static correlation effects.

@article{hollett:114111, abstract = {Restricted Hartree–Fock (RHF) and UHF wavefunctions for beryllium-like ions with nuclear charge 3 ⩽ Z ⩽ 5 are found using a near-complete Slater basis set. The triplet (RHF → UHF) instability and correlation energy are investigated as a function of Z and we find that the instability vanishes for Z > 4.5. We reproduce this surprising behavior using a minimal-basis model and, by comparing with the stretched H2 molecule, conclude that “static” (also known as nondynamical, near-degeneracy, first-order, or strong) correlation comes in two flavors: one that can be captured by UHF and another that cannot. In the former (Type A), there is an “absolute near-degeneracy”; in the latter (Type B), there is a “relative near-degeneracy.” This dichotomy clarifies discussions of static correlation effects.}, added-at = {2011-07-12T00:40:41.000+0200}, author = {Hollett, Joshua W. and Gill, Peter M. W.}, biburl = {https://www.bibsonomy.org/bibtex/295c1609efd2d9dcc3a3413457a6e2267/drmatusek}, doi = {10.1063/1.3570574}, eid = {114111}, interhash = {e35780d8e433208955add606268acc55}, intrahash = {95c1609efd2d9dcc3a3413457a6e2267}, journal = {The Journal of Chemical Physics}, keywords = {chemistry correlation electron fock hartree quantum static theory}, month = {March}, number = 11, numpages = {5}, pages = 114111, publisher = {AIP}, timestamp = {2013-03-13T12:30:53.000+0100}, title = {The two faces of static correlation}, url = {http://link.aip.org/link/?JCP/134/114111/1}, volume = 134, year = 2011 }