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Outer-valence Electron Spectra of Prototypical Aromatic Heterocycles from an Optimally Tuned Range-Separated Hybrid Functional.

Egger DA, Weissman S, Refaely-Abramson S, Sharifzadeh S, Dauth M, Baer R, Kümmel S, Neaton JB, Zojer E, Kronik L - J Chem Theory Comput (2014)

Bottom Line: In particular, we find that with new strategies for an optimal choice of the short-range fraction of Fock exchange, the OT-RSH approach offers a balanced description of localized and delocalized states.We discuss in detail the sole exception found-a high-symmetry orbital, particular to small aromatic rings, which is relatively deep inside the valence state manifold.Overall, the OT-RSH method is an accurate DFT-based method for outer-valence electronic structure prediction for such systems and is of essentially the same level of accuracy as contemporary GW approaches, at a reduced computational cost.

View Article: PubMed Central - PubMed

Affiliation: Institute of Solid State Physics, Graz University of Technology , 8010 Graz, Austria ; Department of Materials and Interfaces, Weizmann Institute of Science , Rehovoth 76100, Israel.

ABSTRACT
Density functional theory with optimally tuned range-separated hybrid (OT-RSH) functionals has been recently suggested [Refaely-Abramson et al. Phys. Rev. Lett. 2012, 109, 226405] as a nonempirical approach to predict the outer-valence electronic structure of molecules with the same accuracy as many-body perturbation theory. Here, we provide a quantitative evaluation of the OT-RSH approach by examining its performance in predicting the outer-valence electron spectra of several prototypical gas-phase molecules, from aromatic rings (benzene, pyridine, and pyrimidine) to more complex organic systems (terpyrimidinethiol and copper phthalocyanine). For a range up to several electronvolts away from the frontier orbital energies, we find that the outer-valence electronic structure obtained from the OT-RSH method agrees very well (typically within ∼0.1-0.2 eV) with both experimental photoemission and theoretical many-body perturbation theory data in the GW approximation. In particular, we find that with new strategies for an optimal choice of the short-range fraction of Fock exchange, the OT-RSH approach offers a balanced description of localized and delocalized states. We discuss in detail the sole exception found-a high-symmetry orbital, particular to small aromatic rings, which is relatively deep inside the valence state manifold. Overall, the OT-RSH method is an accurate DFT-based method for outer-valence electronic structure prediction for such systems and is of essentially the same level of accuracy as contemporary GW approaches, at a reduced computational cost.

No MeSH data available.


Shifted eigenvaluespectra of (a) benzene, (b) pyridine, and (c)pyrimidine obtained from different theoretical schemes: a semilocalfunctional (PBE), a conventional hybrid functional (PBE0) in boththe Kohn–Sham (KS) and generalized Kohn–Sham (GKS) scheme,a self-interaction-corrected (SIC) calculation, with and without additional“stretching” of the energy axis, GW calculations basedon a PBE starting point, and optimally tuned range-separated hybrid(OT-RSH) calculations with two different short-range exchange parameters, α= 0 and α = 0.2. See text for further details on the computationalapproaches. The absolute HOMO energy, in electronvolts, is given atthe top of each column.
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fig5: Shifted eigenvaluespectra of (a) benzene, (b) pyridine, and (c)pyrimidine obtained from different theoretical schemes: a semilocalfunctional (PBE), a conventional hybrid functional (PBE0) in boththe Kohn–Sham (KS) and generalized Kohn–Sham (GKS) scheme,a self-interaction-corrected (SIC) calculation, with and without additional“stretching” of the energy axis, GW calculations basedon a PBE starting point, and optimally tuned range-separated hybrid(OT-RSH) calculations with two different short-range exchange parameters, α= 0 and α = 0.2. See text for further details on the computationalapproaches. The absolute HOMO energy, in electronvolts, is given atthe top of each column.

Mentions: To understand theOT-RSH results in more detail, and to explorethe possible origins of this remaining discrepancy, we performed additionalDFT calculations with several different functionals. Of all DFT functionalsstudied here, the OT-RSH one is the only one capable of obeying theionization potential theorem of eq 3 and, consequently,providing HOMO energies that are close to the experimental IP.3,32 Therefore, in the following comparison, all energies are reportedrelative to the HOMO energy of the respective calculation (which isset to zero). The resulting shifted eigenvalue spectra for the threeprototypical aromatic molecules are shown in Figure 5, with the original HOMO energies shown on top.


Outer-valence Electron Spectra of Prototypical Aromatic Heterocycles from an Optimally Tuned Range-Separated Hybrid Functional.

Egger DA, Weissman S, Refaely-Abramson S, Sharifzadeh S, Dauth M, Baer R, Kümmel S, Neaton JB, Zojer E, Kronik L - J Chem Theory Comput (2014)

Shifted eigenvaluespectra of (a) benzene, (b) pyridine, and (c)pyrimidine obtained from different theoretical schemes: a semilocalfunctional (PBE), a conventional hybrid functional (PBE0) in boththe Kohn–Sham (KS) and generalized Kohn–Sham (GKS) scheme,a self-interaction-corrected (SIC) calculation, with and without additional“stretching” of the energy axis, GW calculations basedon a PBE starting point, and optimally tuned range-separated hybrid(OT-RSH) calculations with two different short-range exchange parameters, α= 0 and α = 0.2. See text for further details on the computationalapproaches. The absolute HOMO energy, in electronvolts, is given atthe top of each column.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4020925&req=5

fig5: Shifted eigenvaluespectra of (a) benzene, (b) pyridine, and (c)pyrimidine obtained from different theoretical schemes: a semilocalfunctional (PBE), a conventional hybrid functional (PBE0) in boththe Kohn–Sham (KS) and generalized Kohn–Sham (GKS) scheme,a self-interaction-corrected (SIC) calculation, with and without additional“stretching” of the energy axis, GW calculations basedon a PBE starting point, and optimally tuned range-separated hybrid(OT-RSH) calculations with two different short-range exchange parameters, α= 0 and α = 0.2. See text for further details on the computationalapproaches. The absolute HOMO energy, in electronvolts, is given atthe top of each column.
Mentions: To understand theOT-RSH results in more detail, and to explorethe possible origins of this remaining discrepancy, we performed additionalDFT calculations with several different functionals. Of all DFT functionalsstudied here, the OT-RSH one is the only one capable of obeying theionization potential theorem of eq 3 and, consequently,providing HOMO energies that are close to the experimental IP.3,32 Therefore, in the following comparison, all energies are reportedrelative to the HOMO energy of the respective calculation (which isset to zero). The resulting shifted eigenvalue spectra for the threeprototypical aromatic molecules are shown in Figure 5, with the original HOMO energies shown on top.

Bottom Line: In particular, we find that with new strategies for an optimal choice of the short-range fraction of Fock exchange, the OT-RSH approach offers a balanced description of localized and delocalized states.We discuss in detail the sole exception found-a high-symmetry orbital, particular to small aromatic rings, which is relatively deep inside the valence state manifold.Overall, the OT-RSH method is an accurate DFT-based method for outer-valence electronic structure prediction for such systems and is of essentially the same level of accuracy as contemporary GW approaches, at a reduced computational cost.

View Article: PubMed Central - PubMed

Affiliation: Institute of Solid State Physics, Graz University of Technology , 8010 Graz, Austria ; Department of Materials and Interfaces, Weizmann Institute of Science , Rehovoth 76100, Israel.

ABSTRACT
Density functional theory with optimally tuned range-separated hybrid (OT-RSH) functionals has been recently suggested [Refaely-Abramson et al. Phys. Rev. Lett. 2012, 109, 226405] as a nonempirical approach to predict the outer-valence electronic structure of molecules with the same accuracy as many-body perturbation theory. Here, we provide a quantitative evaluation of the OT-RSH approach by examining its performance in predicting the outer-valence electron spectra of several prototypical gas-phase molecules, from aromatic rings (benzene, pyridine, and pyrimidine) to more complex organic systems (terpyrimidinethiol and copper phthalocyanine). For a range up to several electronvolts away from the frontier orbital energies, we find that the outer-valence electronic structure obtained from the OT-RSH method agrees very well (typically within ∼0.1-0.2 eV) with both experimental photoemission and theoretical many-body perturbation theory data in the GW approximation. In particular, we find that with new strategies for an optimal choice of the short-range fraction of Fock exchange, the OT-RSH approach offers a balanced description of localized and delocalized states. We discuss in detail the sole exception found-a high-symmetry orbital, particular to small aromatic rings, which is relatively deep inside the valence state manifold. Overall, the OT-RSH method is an accurate DFT-based method for outer-valence electronic structure prediction for such systems and is of essentially the same level of accuracy as contemporary GW approaches, at a reduced computational cost.

No MeSH data available.