Time-dependent density-functional tight-binding method with the third-order expansion of electron density.

• Nishimoto, Yoshio

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.

Journal

• The Journal of chemical physics

  The Journal of chemical physics 143 (9), 094108-, 2015-09-04

  AIP Publishing

Keywords

• Physical and Theoretical Chemistry
• General Physics and Astronomy

Details

• CRID: 1050564285772233984
• NII Article ID: 120005678169
• NII Book ID: AA00694991
• ISSN: 00219606
• ISSN: 10897690
• DOI: 10.1063/1.4929926
• HANDLE: 2433/202573
• Web Site: https://pubs.aip.org/aip/jcp/article-pdf/doi/10.1063/1.4929926/15500414/094108_1_online.pdf
• Text Lang: en
• Article Type: journal article
• Data Source:
  • IRDB
  • Crossref
  • CiNii Articles
  • KAKEN