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Title: Time-dependent density-functional tight-binding method with the third-order expansion of electron density.
Authors: Nishimoto, Yoshio  kyouindb  KAKEN_id
Author's alias: 西本, 佳央
Issue Date: 4-Sep-2015
Publisher: AIP Publishing
Journal title: The Journal of chemical physics
Volume: 143
Issue: 9
Thesis number: 094108
Abstract: We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of the third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well.
Rights: © 2015 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in [J. Chem. Phys. 143, 094108 (2015)] and may be found at http://dx.doi.org/10.1063/1.4929926
URI: http://hdl.handle.net/2433/202573
DOI(Published Version): 10.1063/1.4929926
PubMed ID: 26342360
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