Impact of exact exchange in the description of the electronic structure of organic charge-transfer molecular crystals
Type
ArticleKAUST Department
KAUST Solar Center (KSC)Laboratory for Computational and Theoretical Chemistry of Advanced Materials
Material Science and Engineering Program
Physical Science and Engineering (PSE) Division
Date
2014-10-21Permanent link to this record
http://hdl.handle.net/10754/555960
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We evaluate the impact that the amount of nonlocal Hartree-Fock (%HF) exchange included in a hybrid density functional has on the microscopic parameters (transfer integrals, band gaps, bandwidths, and effective masses) describing charge transport in high-mobility organic crystals. We consider both crystals based on a single molecule, such as pentacene, and crystals based on mixed-stack charge-transfer systems, such as dibenzo-TTF–TCNQ. In the pentacene crystal, the band gap decreases and the effective masses increase linearly with an increase in the amount of %HF exchange. In contrast, in the charge-transfer crystals, while the band gap increases linearly, the effective masses vary only slightly with an increase in %HF exchange. We show that the superexchange nature of the electronic couplings in charge-transfer systems is responsible for this peculiar evolution of the effective masses. We compare the density functional theory results with results obtained within the G0W0 approximation as a way of benchmarking the optimal amount of %HF exchange needed in a given functional.Citation
Impact of exact exchange in the description of the electronic structure of organic charge-transfer molecular crystals 2014, 90 (16) Physical Review BPublisher
American Physical Society (APS)Journal
Physical Review BAdditional Links
http://link.aps.org/doi/10.1103/PhysRevB.90.165205ae974a485f413a2113503eed53cd6c53
10.1103/PhysRevB.90.165205