Document Type
Article
Publication Date
4-26-2012
Abstract
In a recent article, we showed that configuration interaction singles (CIS) has a systematic bias against charge-transfer (CT) states: CT vertical excitation energies are consistently too high (by 1-2 eV) as compared with non-CT energies [J. E. Subotnik, J. Chem. Phys. 137, 071104 (2011)]. We now show that this CIS error can be corrected approximately by performing a single Newton- Raphson step to reoptimize orbitals, thus establishing a new set of orbitals which better balances ground and excited state energies. The computational cost of this correction is exactly that of one coupled-perturbed Hartree-Fock calculation, which is effectively the cost of the CIS calculation itself. In other words, for twice the computational cost of a standard CIS calculation, or roughly the same cost as a linear-response time-dependent Hartree-Fock calculation, one can achieve a balanced, size-consistent description of CT versus non-CT energies, ideally with the accuracy of a much more expensive doubles CIS(D) calculation.
Recommended Citation
Liu, X., Fatehi, S., Shao, Y., Veldkamp, B. S., & Subotnik, J. E. (2012). Communication: Adjusting charge transfer state energies for configuration interaction singles: Without any parameterization and with minimal cost. The Journal of Chemical Physics, 136(16), 161101. https://doi.org/10.1063/1.4705757
Publication Title
The Journal of Chemical Physics
DOI
10.1063/1.4705757
Comments
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in X. Liu et al., J. Chem. Phys. 136, 161101 (2012) and may be found at http://dx.doi.org/10.1063/1.4705757