TY  - JOUR
A1  - Sutton, Christopher
A1  - Körzdörfer, Thomas
A1  - Gray, Matthew T.
A1  - Brunsfeld, Max
A1  - Parrish, Robert M.
A1  - Sherrill, C. David
A1  - Sears, John S.
A1  - Bredas, Jean-Luc
T1  - Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - We investigate the torsion potentials in two prototypical pi-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains.
Y1  - 2014
U6  - https://doi.org/10.1063/1.4863218
SN  - 0021-9606
SN  - 1089-7690
VL  - 140
IS  - 5
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Körzdörfer, Thomas
A1  - Parrish, Robert M.
A1  - Marom, Noa
A1  - Sears, John S.
A1  - Sherrill, C. David
A1  - Bredas, Jean-Luc
T1  - Assessment of the performance of tuned range-separated hybrid density functionals in predicting accurate quasiparticle spectra
JF  - Physical review : B, Condensed matter and materials physics
N2  - Long-range corrected hybrid functionals that employ a nonempirically tuned range-separation parameter have been demonstrated to yield accurate ionization potentials and fundamental gaps for a wide range of finite systems. Here, we address the question of whether this high level of accuracy is limited to the highest occupied/lowest unoccupied energy levels to which the range-separation parameter is tuned or whether it is retained for the entire valence spectrum. We examine several pi-conjugated molecules and find that orbitals of a different character and symmetry require significantly different range-separation parameters and fractions of exact exchange. This imbalanced treatment of orbitals of a different nature biases the resulting eigenvalue spectra. Thus, the existing schemes for the tuning of range-separated hybrid functionals, while providing for good agreement between the highest occupied energy level and the first ionization potential, do not achieve accuracy comparable to reliable G(0)W(0) computations for the entire quasiparticle spectrum.
Y1  - 2012
U6  - https://doi.org/10.1103/PhysRevB.86.205110
SN  - 1098-0121
VL  - 86
IS  - 20
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Körzdörfer, Thomas
A1  - Parrish, Robert M.
A1  - Sears, John S.
A1  - Sherrill, C. David
A1  - Bredas, Jean-Luc
T1  - On the relationship between bond-length alternation and many-electron self-interaction error
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - Predicting accurate bond-length alternations (BLAs) in long conjugated molecular chains has been a major challenge for electronic-structure theory for many decades. While Hartree-Fock (HF) overestimates BLA significantly, second-order perturbation theory and commonly used density functional theory (DFT) approaches typically underestimate it. Here, we discuss how this failure is related to the many-electron self-interaction error (MSIE), which is inherent to both HF and DFT approaches. We use tuned long-range corrected hybrids to minimize the MSIE for a series of polyenes. The key result is that the minimization of the MSIE alone does not yield accurate BLAs. On the other hand, if the range-separation parameter is tuned to yield accurate BLAs, we obtain a significant MSIE that grows with chain length. Our findings demonstrate that reducing the MSIE is one but not the only important aspect necessary to obtain accurate BLAs from density functional theory.
Y1  - 2012
U6  - https://doi.org/10.1063/1.4752431
SN  - 0021-9606
VL  - 137
IS  - 12
PB  - American Institute of Physics
CY  - Melville
ER  -