Moore Conrad C, Staroverov Viktor N
Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
J Chem Phys. 2024 Sep 28;161(12). doi: 10.1063/5.0228216.
The kinetic energy density of electrons and the gradient of the electron density have pronounced jump discontinuities at the positions of the atomic nuclei in molecules. Certain exact relations then imply that molecular Kohn-Sham exchange-correlation potentials may also be discontinuous at atomic nuclei. Here, we confirm that exchange-correlation potentials derived from Hartree-Fock and correlated wavefunctions within Slater-type basis sets do exhibit such discontinuities. Despite their persistence even in large basis sets, these discontinuities are almost certainly artifacts of basis set finiteness and are expected to disappear in the basis-set limit. The findings imply that imposing electron-nucleus cusp conditions in spherically averaged form may not always be appropriate.
电子的动能密度和电子密度的梯度在分子中原子核的位置处有明显的跳跃间断点。某些精确关系进而表明，分子的科恩-沈（Kohn-Sham）交换关联势在原子核处也可能是间断的。在这里，我们证实，在斯莱特型基组内由哈特里-福克（Hartree-Fock）和相关波函数导出的交换关联势确实表现出这种间断性。尽管即使在大基组中这些间断性仍然存在，但它们几乎肯定是基组有限性的伪像，并且预计在基组极限下会消失。这些发现意味着，以球平均形式施加电子-原子核尖点条件可能并不总是合适的。
