Accurate adiabatic connection curve beyond the physical interaction strength

In order to better approximate and understand the exchange-correlation functional in density functional theory, the adiabatic connection curve is accurately calculated beyond the physical interaction strength using a simulated scaling method. This is done for Hooke’s atom, two interacting electrons in a harmonic well potential. Extrapolation of the accurate curve to the infinite-coupling limit agrees well with the strictly correlated electron hypothesis. The interaction strength interpolation is shown to be a good, but not perfect, fit to the adiabatic curve. Arguments about the locality of functionals and convexity of the adiabatic connection curve are examined in this regime. © 2003 American Institute of Physics. @DOI: 10.1063/1.1579465#