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Working within the Tamm-Dancoff approximation, we calculate the derivative couplings between time-dependent density-functional theory excited states by assuming that the Kohn-Sham superposition of singly excited determinants represents a true electronic wavefunction. All Pulay terms are included in our derivative coupling expression. The reasonability of our approach can be established by noting that, for closely separated electronic states in the infinite basis limit, our final expres- sion agrees exactly with the Chernyak-Mukamel expression (with transition densities from response theory). Finally, we also validate our approach empirically by analyzing the behavior of the derivative couplings around the T1/T2 conical intersection of benzaldehyde.


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 Q. Ou et al., J. Chem. Phys. 141, 024114 (2014) and may be found at

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The Journal of Chemical Physics



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Chemistry Commons



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