Abstract
One of the several problems that plague majority of density functional
theory calculations is their inability to properly account for
long-range correlations giving rise to dispersion forces. The recently proposed many-pair expansion (MPE) [T. Zhu et al., Phys. Rev. B 93,
201108(R) (2016)] is a hierarchy of approximations that
systematically corrects any deficiencies of an approximate
functional to finally converge to the exact energy. This is achieved by
decomposing the total density into a sum of two-electron
densities and accounting for successive two-, four-, six-,…
electron interactions. Here, we show that already low orders of MPE expansion recover the dispersion energy accurately. To this end, we employ the Pariser-Parr-Pople Hamiltonian and study the behavior of long-range interactions in trans-polyacetylene
as well as stacks of ethylene and benzene molecules. We also
show how convergence of the expansion is affected by electron
conjugation and the choice of the density partitioning
Original language | English |
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Article number | 024111 |
Journal | Journal of Chemical Physics |
Volume | 146 |
Number of pages | 10 |
ISSN | 0021-9606 |
DOIs | |
Publication status | Published - 2017 |
Externally published | Yes |